To properly make tandoori chicken, you need a special oven called a tandoor, from which the dish takes its name. Fortunately, it turns out pretty well on a grill, and now that it's summer, it's a perfect time to make it. The yogurt coating simultaneously adds flavor and keeps the chicken moist, which can be hard to do. You can bring it to a cookout, letting it marinate on the way, and everyone will be asking "Who brought the orange chicken?" and "Is there any more?"
Its also super easy to make, with three ingredients besides the chicken: yogurt, lemon juice, and a boxed spice mix. For the spice mix, I use Shan Tandoori Chicken BBQ. It comes with instructions on the box, and I'm sure that makes great chicken, too, but I don't follow that recipe. It may feel like cheating to use a mix, but if you made it from scratch, it would still feel like cheating when you added the food coloring.
For about 2 pounds of chicken, I use half the spice mix, the juice of a whole lemon, and 10oz of yogurt. The color when you're done should be a bright orange, and there should be enough to liberally coat the chicken. I prefer to use boneless thighs, but any cut of chicken will work (in these pictures, I used breasts). The chicken should be cut into pieces so it will cook faster without drying.
After a half to several hours of marinating, throw it on the grill. How long you need to cook it will depend upon the particulars of the grill, but the coating should be a good indication of how well done it is. If you haven't cut the pieces too thick, they will be perfectly done when the yogurt no longer looks wet and there is a little but of char.
This particular batch was eaten with salad, but most commonly I just serve it on a plate with other grilled foods. If it is being served by itself, traditional complements include sliced cucumbers, raw red onion slices, and lemon wedges.