Cut small slits in the chicken and place it in a bowl or shallow dish.
In a bowl, combine the salt, yogurt, garam masala, and turmeric.
Juice one of the lemons and finely chop the onion and garlic and add the juice, onion, and garlic to the yogurt mixture.
Spread the yogurt mixture over the chicken.
Cover and refrigerate for 24-48 hours.
Preheat an outdoor grill for medium high heat and cook the chicken until the center is no longer pink and it is cooked through (about 15-20 minutes depending on grill heat).
Cut the remaining lemon into wedges and garnish the chicken with cilantro and lemon wedges.
Notes
You can double the ingredients for the marinade and easily have enough to marinate 5 pounds of chicken.