Preheat broiler and lightly oil rack of a broiler pan. Stack tortillas and wrap in foil. Stir together hoisin, soy, honey, ginger, vinegar, garlic, and cayenne in a 1 to 1½-quart saucepan. Toss chicken with 3 tablespoons sauce in a large bowl to coat, then broil 2 to 3 inches from heat, without turning, rotating pan halfway through broiling, until cooked through and deep golden, about 10 minutes. Transfer to a cutting board and let stand, uncovered, 5 minutes.