Every Chowk & Coal kitchen has a clay tandoor at its centre. It is lit a little after eight in the morning, and it takes about two hours to come up to working heat. By the time the first order arrives the walls are close to 480°C.
A gas tandoor reaches that temperature faster and holds it with less work. We tried one in 2018 and took it out after three weeks. The breads were paler and the kebabs tasted clean in a way we did not like.
Charcoal does two things gas does not. It gives off dry, radiant heat, so the outside of a naan blisters before the inside dries. And when marinade and fat drip on to the coals, the smoke that comes back up is what people recognise as the taste of a tandoor.
Clay matters too. The walls hold heat and release it evenly, and bread sticks to clay in a way it does not stick to steel. Our tandoors are relined about once a year, and a new lining is seasoned with jaggery, mustard oil and salt before it is used.
It costs us more in fuel and in skilled hands. A tandoor cook needs a couple of years before he can judge a fire by looking at it. We think the food is better for it, so the charcoal stays.