In a shallow glass baking dish combine fresh lemon juice with olive oil, garlic and crushed peppercorns. Mix together with a fork. Place chicken breasts in baking dish and turn several times to coat with mixture. Let marinate for 30 minutes. Heat an indoor iron grill pan or outdoor grill until very hot. Sprinkle chicken breasts with salt and cook for 3 to 5 minutes on each side or until cooked through.