If you like the wonderful breads and meats at your favorite Indian restaurant, you will enjoy this article about bringing the 5,000 year old tandoori oven technology to the modern era
“The traditional tandoor that Mr. Levy set out to copy 30 years ago was typically an unfired vessel, the clay walls strengthened with straw and animal hair.
“It was very unsanitary,” Mr. Levy said, adding that ovens shipped to the United States “often arrived from India broken, or would crack with extended use.” The tandoor’s shape, a cylinder with sloped clay walls, has remained essentially unchanged for 5,000 years.
Mr. Levy’s first innovation was to fashion the body from a blend of earthenware and stoneware, the former chosen for its modeling and expansion properties, the latter for its ability to withstand high heat without cracking. For porosity (an essential quality so that flatbreads can cling to the oven’s inner walls), he added finely ground fired clay, known as grog. For insulation and extra strength, he developed a clay and vermiculite mixture that could be baked onto the exterior of the pot.
Finally, he devised a sturdy stainless steel housing, so the tandoor could be sold and installed as a movable, freestanding unit. “