My Homemade Tandoor Oven
Trip Start Dec 08, 2008
27Trip End Dec 24, 2008
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For those that read the previous entries in my travel blog, you'll remember that towards the tail end of our trip to India, I was told that tandoor ovens are incredibly cheap to purchase over there. Like 500 rupees (about $10-$12 USD) but of course the problem is that they are very heavy, because they are essentially a giant chunk of clay. And on top of that, they are very fragile. So while I was able to find one at a very affordable price, by the time it was packed safely enough to ship somewhere, it weighed about 40-50 kilograms (90-110 pounds). That's way to heavy to check as baggage, and it would cost a fortune to ship back home by any method other than ocean liner. So my dreams of having a tandoor at home were dashed for the moment
But alas, I wasn't going to give up so easy. As soon as we got back to the states, Rebecca left again to go join her family. So I'd be by myself for a couple of days after christmas with nothing to do. So I decided to read a hundred articles on the internet about building a back-yard tandoor over, and devise a plan to build my own out of common items found at your local home improvement store.
Looking back in hindsight, my first design was really lacking. I thought that a tandoor wasn't much more than clay (or stone) walls around something really hot. So my plan was to cut the bottom off of a cheap planter pot, attach the wide end to a metal BBQ grill somehow, then invert the whole thing and put it on top of one of those super-jet-burners that they use for boiling huge pots of water while camping. So I set out on the 26th of December to see what kind of after-christmas sales I could find on camping equipment. As luck would have it, I found exactly the kind of burner I was looking for at G.I. Joes (I guess it's now just called "Joes") which is a chain store in the pacific northwest that carries all sorts of camping, sporting, fishing and outdoorsing equipment... and car parts... ??? figure that one out. But whatever, it had exactly the kind of burner I wanted on sale for $34.99
Next I run over to the local home improvement store "Jerry's", which I think is unique to Eugene/Springfield. (We've got Home Depot and Lowe's too, but I try to shop local when I can) And I head out to the garden center where I find that they've got a huge section of their pottery on 75% off! Score! I pick up this nice large white pot and a round BBQ grill that fits the mouth just about perfectly. At this point, I knew that I didn't just want exposed super-heated stone on the outside of my over, so I needed something to protect myself and others from touching it. I wandered around the store for probably an hour looking for inspiration. I asked a couple of store employees if they had any ideas for high-temp insulation, but we couldn't come up with anything. Then I started thinking "I just need a big can to throw over the top of it!" and then I ran over to the garbage can isle praying that people still carried metal garbage cans. Sure enough, there it was, the perfect-sized garbage can, at a very affordable price as well. So I purchases all my goods and returned to my garage to start construction.
I get home and I remember reading all these stories about people that cut the bottoms off their pots with an angle grinder
At this point, I toy with the idea of giving up, but I decide to trudge on, and I go out to try the new blade with the terra cotta pot. Ahhhh! Much better! It's not quite like a hot knife to butter. It's more like a cold serratted knife to butter that's been frozen to absolute zero. Suffice it to say that I get the entire bottom cut off, but it takes about an hour to make the entire cut
While my pot was drying, I decided to read up more on how tandoors work. That's when I realized that the tandoor is more than just a clay-walled oven. They work by essentially building up and trapping the heat inside so much that they can get up to insanely hot temperatures. Then I realized that there was no way my tandoor was going to get hot enough with a 17 inch mouth over the top of a 12 inch burner (due to excess airflow) and I also didn't incorporate any kind of insulation into my design
I spend another hour cutting the bottom off the second pot, swap it with the pot that's drying on the stove, so it can get some of it's water out as well. I then mortar the top and bottom lips of the first pot and wait a while for everything to dry. After sufficient time had passed, I blob a bunch more mortar around the lip of the upright pot, and drop the second pot on top of the first. Then I commence in applying a nice thick layer of mortar to the inside and outside of the joint between the two pots. Around the outside, I cut the chicken-wire down to the right size, and I wrap it around the two pots at the thickest part. I use two pairs of small vice grips to make sure it's tight. Then I mortar over the top of that. I place the whole concoction over the top of my stove burner (set to medium low heat, maybe 4 of 10) place the lid on it, and leave it overnight (about 8-12 hours).
The next day, I spend a little more time reading about tandoors and I discover all this information about curing your tandoor oven
So far so good! Now it's time for final assembly! I measure the bottom mouth of the clay liner and cut a circular hole in the bottom of the garbage can that is about 1 inch narrower all the way around. That way I would have a nice little shelf to rest the skewers on when they are in the oven cooking. And I gotta say the garbage can idea is brilliant because the bottom has all these circular ripples in it for strength, so cutting a perfectly circular hole that is also exactly centered is really quite easy because you just pick the ripple closest to the size you need and cut along that, and voila
I measured the lip of the liner at the top of the can, and I cut a nice circular hole in the garbage can lid. Again, using the ripples in the lid as a guide, I was able to cut a very round, very centered hole, but when I fitted it on the top of my contraption, it didn't line up
I placed my tandoori-can on the burner and turned the propane on just a crack, and let it go for awhile. I've got one of those kitchen thermometers with a remote probe, so I dropped that inside to see how how it was getting. After about 20 minutes of running with the lid off, the temp had stabilized to about 180 degrees I think. But if I put the lid on, and dropped the probe in through the whole in the middle, the temp shot right up past 400 degrees (that's where my termometer maxes out) in a matter of minutes. If I took the lid off, the temp would slowly fall to some stabilized temp much lower. I also noticed when the lid was on, the outside of the can would get much hotter. After a little investigation I realized that with the lid on, the inside heats up, and starts pouring out the bottom hole of the clay liner and overflowing around the bottom of the can and starts climbing up the outside of the can
I decided I needed to block the bottom hole a little and force whatever air is coming in to pass by something that is hot, and also give the heat rays inside the tandoor something to bounce off of and return back upwards instead of escaping. The solution proved to be very easy: I made a small basket out of the extra chicken-wire I used for reinforcing the joint, and forced that down to the bottom of the liner, and poured in a bunch of lava rock that they use for the bottom of normal gas BBQ grills. The instructions on the package of lava rocks actually says you need to fire them up by themselves for about 15-20 minutes. That is because on their first heating, they burn off their outer layer and that releases a bit of a smell which could possibly effect your food. So after dropping them in, I fired up the burner to low at first, then up to medium after about 4 or 5 minutes. Then I let it sit for another 15 minutes. The bottom layer of lava rocks started glowing red, and I could already tell that the heat inside that tandoor was much more stable than before
I only had one skewer at this point, a piece of metal stock that is probably 3/8in diameter by 6 feet long. I sharpened the tip with my bench grinder and stuck a bunch of chicken on it. I dropped that in and set the timer for 10 minutes. Not quite enough, but after a 2nd 10 minutes, it was a little overcooked (but still delicious I'm told). So after getting the chicken off (which was quite a hassle, remember to oil the skewers before you use them) I dropped the skewer in a plastic garbage can filled with water to cool it off, then I prepped a 2nd skewer and dropped that in 17 minutes. That one came out just about right. At this point I thought the temp inside the tandoor had equalized, so I dropped in a 3rd skewer and set the timer for 15 minutes and walked away....
When the timer went off I walked out and noticed that the lid I was using had cracked, so I pulled it off and saw that the chicken on the skewer was burning. Not burning like the edges were black, but burning like a log in a roaring bonfire! I quickly pulled the skewer out and the whole thing kept burning quite easily. So I shut off the propane, dropped the whole skewer in the water tank to put it out. I put my hand over the top of the tandoor for a second, and realized I couldn't even hold it 10 inches over the top of the mouth for longer than a tenth of a second without feeling like my hand was burning
The next morning I went out to check on it, and the clay liner was perfectly in tact, although the curing glaze I'd painted on the inside had been completely incinerated. I also noticed that the mortar I'd put on the bottom of the garbage can had all cracked and fallen off. At first this really worried me, but then I realized that it looked like it was nothing more than a different heat expansion properties between the steel and the mortar. The mortar was designed to stick to stoneware (which is does very well) and it is probably designed to expand at the same rate that fireplace bricks do. The steel of the garbage can obviously expands differently at different heats, so the mortar wasn't able to hold on, so it just cracked and sluffed off. A little more concerning, however, is that the wire basket I placed the lava rocks in. I poked at that a couple of times, and it seems like the metal had crystalized (or whatever happens when it reaches super high temperatures and then cools down)... because as soon as you poke it, the individual strands would just shatter. It actually reminded me of the silk mantles that you use in coleman lanterns for some reason. And I hypothesize that as long as I don't move anything, it'll probably be fine, but as soon as I lift the can off the burner, that basket with probably break and all the lava rocks will fall out
So I put a couple more coats of the curing glaze on the inside, then went out to find a thermometer to put inside this thing so I know how hot I'm working with. The solution ended up being quite simple... Jerry's has a magnetic thermometer that is for wood-stoves. It's designed to stick to the base of the chimney I think (to tell you if you're getting close to a chimney fire), and it goes up to about 800F. It's all metal, including the readout, so the whole thing can sit inside a very hot environment and not be any worse for wear. So I took a strip of steel I had sitting around my shop area and make a quick couple of bends with a vise and my big 3lb sledgehammer (I love that hammer!) and made a bracket that hangs over the top of the tandoor and hooks on the edge of the garbage can lid, and drops down into the opening about 5 or 6 inches. I fired up the tandoor after installing the thermometer and it doesn't really read anything below about 200F, but between 200F and 600F it did a good job of telling me approximately how hot it was inside.
I had a big party coming up where I wanted to show off what the new toy could do. So I got about 15lbs of chicken breast tenderloins and started them marinating. I also bought 4 more pieces of steel stock from Jerry's. This time I got the 1/4 inch by 6ft plated rods. I cut each one in half, which yielded 8 skewers of 3ft per. 3ft means that I've only got about 8-10inches sticking out the top which isn't really enough to work with. So I found a small pile of wooden dowels in my shop, and cut a bunch of 1ft sections, drilled holes in the end, and jammed the skewers into the end of the dowels
In addition to the 15lbs of chicken, I sliced up about 5 lbs of potatoes into 1/2in rounds, and and equal amount of onions cut into eights. When it came time to make up the skewers, I would alternate potatoe-chicken-onion-chicken-potatoe-chicken-onion and so on until I'd filled up the whole 14inches of cooking space. The purpose of this is that I noticed when it's just a big bundle of chicken on a skewer it tends to fuse into a solid mass which makes it harder to both get off the skewer and cook all the way through. It also added a bunch of edible stuff to each skewer, as the big party might have as many as 17 people attend. I might also mention that after chopping the onions and potatoes, I threw them in a big bowl with peanut oil, and a mix of indian spices (ground cumin, corriander and turmeric) and tossed it all together to get the spices mixed around.
On the day of the party, I started the tandoor about 90 minutes before I wanted to start cooking to get it heated up. I think the temp equalized within 40 minutes, and it never really got above 275F. So I turned up the propane and found that the temp would equalize within about 15 minutes after it was pre-heated. So I kept adjusting it until I got the temp to about 500F consistently, and started cooking. At 500F, each skewer would go in for at least 20 minutes
The next thing to try was naan, which is a traditional indian flatbread that is cooked by flattening out the dough into a little pancake-like patty and slapping it to the inside wall of a tandoor oven. It starts bubbling and cooking immediately, and they use a little hook and scraper to retrieve them off the walls when they are done cooking. So I'd actually fashioned a hook out of another piece of metal like my skewers, and I make a scraper by attaching a cheap wood-handled frosting spreader I got from the local kitchen supply store to the end of another piece of metal rod. I flattened out the dough, slapped it to the inside, and it started cooking immediatly just like it should. I was estatic and I was doing my own happy dance around the tandoor at that point. You see, we've been throwing these parties every month for the past year, and each time I try to make naan we can only cook them one at a time on a cast-iron griddle, and they just don't cook the same. It also takes the better part of 45-minutes to get them all cooked. Once I master the process inside the tandoor, it should cut that time to less than half, and they end up tasting better as well. So it's win-win all around!
I realized this post is a little long-winded, but I know there are several people out there on the internet are wishing they had their own tandoor oven just like I was
In the photos I included a cost breakdown to give you an idea of how much this project cost. I'm pretty sure I could have gotten a propane tank cheaper somewhere, and a lot of people already have one sitting around. That was defenitely a large part of the cost, but overall I'm ok with the price. I could probably get a decent backyard BBQ grill for $230, but the way I see it, the tandoor can do almost everything a normal grill can do, and lots of things it can't do. And I also get an awesome burner for boiling water while camping as well. So I think this is defenitely a better deal.
Update (1 year later):
I've now been using the tandoor on and off again for the past year. The wire basket inside eventually disintegrated completely, which caused me to rebuilt the bottom of the unit. For the rebuild, used a freshly-cleaned shop-vac and sucked out all the Perlite from the top section of the garbage can, then I gently tipped it on it's side and pushed, pulled and jiggled until I got the liner out in one piece. This led to the bottom half of the Perlite going everywhere. Using the shop-vac again, I got all the Perlite sucked up, then I put the original metal grill (12 or 15") in the bottom of the garbage can, then I set the liner on top of that and poured in all the Perlite from the shopvac
The original bracket for the thermometer only lasted one or 2 sessions, it got in the way of the lid too much. To I ended up drilling a whole in the lid (which is a trash can lid from a small-sized metal garbage can) and placing the thermometer over that whole. That mostly worked, but after a couple of months it started sticking, and by now if it moves at all it is so inaccurate that it's not even worth spending the brain cells to read it. What I really need is one of those IR laser themometers, I just need to make sure it can read up to 1100 or 1200 degrees (F).
Over the year, we've used it for dinners maybe 20 times, and I still struggle with naan sticking to the side correctly. I think that terra cotta just doesn't react the same, and I frequently wish I had a horizontal surface I could drop inside for baking flatbread. But sometimes I get it to work, and when it works, everybody raves about how amazing the bread is. But for skewered items, it is awesome. Tandoori Chicken, Lamb kebabs for gyros, and there is simply no better way to make roasted eggplant.