The bright orange that's typical of tandoori chicken, and of dishes made with tandoori chicken, just comes from red food coloring mixed with the yogurt (or sour cream, if you're sub'ing) in the marinade. Nothing complicated about it -- all my Indian cookbooks name the red food coloring.

Haven't done an intro yet, but I will eventually. In any case, I used to cook for a living, and Indian was among my favorite types of cooking. Love the complexity of flavors. This recipe is very much like the butter chicken recipe I use.