Does authentic Chicken Tandoori (however one spells it) have red food coloring in it?
My guess is that it’s a spice, not food colorinh.
Joe
For what it may be worth, I spent many years thinking that I didn’t like Indian food when it turned out I just didn’t like the tandoori everyone kept urging on me.
Try something else.
The way it was explained to me is that the authentic stuff is red because of the presence of gargantuan amounts of lal mirch (red pepper). The stuff we get here in the Land of the Free is colored red with food dye to simulate the authentic recipe, because we can’t handle the real deal.
Oh, I like it, I’m just surprised to find food coloring in the recipe.
Washoe is probably right. 
Often annatto is used, which could be considered either a food coloring or a spice.
I just checked my copy of Madhur Jaffrey’s Indian Cooking. According to her, the color is due to the use of food coloring.