I've been looking at tandoor ovens for a while now. But they get expensive. After studying several designs online, I decided to make my own.
Forty bucks later, I was cooking skewers of yogurt-marinated beef.
Step 1: What You Need...
16" red clay pot. Make sure it is made in the USA, as you don't want one that contains lead.
An old barrel smoker, or similar sized barrel.
Four 8" metal straps. Make sure they are not galvanized. Zinc poisoning sucks.
Vermiculite insulation (I used horticultural vermiculite)
1-24" square of hardibacker or other cement board.
My total expense was under $40, versus the $1000 plus you can pay for a 'bought' tandoor oven.
Step 2: Cut the Bottom Off the Clay Pot
Mark a line one inch down the side of the clay pot. I used a 4in angle grinder with a masonry blade to cut it, but you can use a hacksaw or hand type tile saw if you have 328 hours to do it that way. I didn't. So I took five minutes to do it. I carefully scored the line with the grinder, then went back around two more times to cut through it completely.
Step 3: Cut Six Inches Off the Bottom of the Barrel Smoker
This one is trickier. You have to do math. Take all the hardware off the smoker. I was able to leave the handles on, but everything else had to come off. Cut the bottom of the barrel smoker off with a hacksaw or whatever. I measured it so that it would be about one inch above the clay rim when finished. That mean six inches.
Then slide the barrel over the upside down pot. You may have to use a mallet or bend the metal a little, depending on the thickness of your pot.
Step 4: Metal Straps
In this case, my picture didn't come out, but curl the ends of the straps so they hook over the bottom of the clay pot. Then secure them to the side of the barrel with self-drilling screws. This will keep the pot from sliding of the barrel.
Step 5: Add Your Insulation.
Fill the space with Vermiculite. I used it because it's cheap and readily available. Mineral cloth would work well too, but do NOT use fiberglass insulation. Gravel works well but it would be pretty heavy.
Step 6: Add a Cover to Make It Pretty
I cut a donut out of Hardibacker and placed it over the rim of the inverted clay pot. Your measurements will vary on this depending on the size of your barrel and the size of your clay pot.
Step 7: Start Cooking
I have mine set up on the base of my new smoker, and it works great. In fact, it's almost like a rocket stove thanks to the venting. But you can set it on bare ground as well. In either case, you get the right temperatures for naan bread or yogurt marinades.
My pro upgrade was to reinstall the top hardware on the barrel so I could put the old lid on it. I also added a better thermometer to it.
I made my skewers from a 48" piece of plate steel that I cut in the middle (at a slight angle) and sharpened to allow them to pierce meat easily. You can buy them pretty cheaply as well.