Chicken tandoori style:Place the chicken in a small dish.Make three cuts in each breast, then rub each side with salt and sprinkle with lemon juice.Whisk the yogurt with garlic, ginger, chili pepper, garam masala, and turmeric. Pour over the chicken and turn to coat evenly.Cover and refrigerate for at least 4 hours or overnight.Potato salad:Boil the potatoes in salted water until tender (cooking time will depend on the size of your potatoes).Let them cool, peel, and cut into cubes.In a bowl, whisk the oil with lime juice, garlic, garam masala, salt, and Cayenne pepper.Add the cilantro, green onions, and potato cubes and mix well.Cover the bowl with plastic wrap and refrigerate to allow the flavors to meld.Cooking the chicken:Oil the grill and preheat the barbecue to medium-high heat.Remove the chicken from the marinade and place it on the grill.Cook for about 5 minutes on each side.Place on a cutting board and slice the chicken into strips.Spread the potatoes on a serving plate and arrange the chicken strips on top and serve immediately.