Tandoori masala is a mixture of spices specifically for use with a tandoor, or clay oven, in traditional north Indian and Afghan cooking. The specific spices vary somewhat from one region to another, but typically include garam masala, garlic, ginger, cumin, cayenne pepper, and other spices and additives (e.g. lemon juice ...). The spices are often ground together with a pestle and mortar.
Tandoori masala is used extensively with dishes as Tandoori chicken. In this dish chicken is covered with a mixture of plain yogurt, and tandoori masala. The chicken is then slow-roasted in the tandoor. The chicken prepared in this fashion has a pink-colored exterior and a savory flavor.
If prepared yourself, the masala can be stored in airtight jars for up to 2 months. However, nowadays, packets or canisters of tandoori chicken masala are also readily available at major Indian supermarkets, with varying tastes depending on the brand. This convenience has led to many Indians buying the masala rather than making it at home.