Pull the skin off the chicken pieces, remove all visible fat, and discard. Prick the chicken all over with a fork and make diagonal slashes, 1/2 inch deep and one inch apart, on the meat. Mix together the lemon juice, food coloring, if using, cumin, Garam Masala, red pepper, and salt and brush over the chicken, pushing the marinade into the slits. Combine the yogurt, ginger, and garlic and pour over the chicken. Mix, turning several times, to coat the chicken pieces evenly with the marinade. Cover and marinate at room temperature for one hour or refrigerate for 8 hours or up to 2 days. If the chicken has been refrigerated, bring to room temperature before cooking. If placing on skewers, slide meat down metal skewers prior to grilling. If grilling, heat the grill and place the grill rack at least 5 inches from the heat. If roasting, place the oven rack in the middle position and preheat the oven to 500 degrees. Remove the chicken from the marinade and coat generously with usli ghee. To grill, place meat side down, on the grill rack. To roast, place the chicken, meat side down, on a wire rack set over a jelly-roll pan. Grill or roast the chicken, turning 3 or 4 times during cooking, until the juices run clear, about 35 minutes. Brush the chicken with the remaining usli ghee and transfer to a platter. Surround the chicken with slices of onion, tomato, and cucumber and serve. The tandoori marinade is traditionally colored bright orange using natural food coloring. This is purely for visual effect. You can omit the color if you prefer.
Recipe Courtesy of Julie Sahni, author Introduction to Indian Cooking