To make brine. Bring the Water (5 fluid ounce), Salt (2 ounce), and Granulated Sugar (1/2 teaspoon) to a boil, remove from heat, add the Ice (15 ounce) to cool the brine down quickly before you add the chicken. Brine the Boneless, Skinless Chicken Breast (1) overnight.
The next day, butterfly the chicken breasts.
Flatten the breasts and score without cutting all the way through.
Season with Kosher Salt (to taste) and Sriracha (to taste) on both sides.
Add Soy Sauce (to taste) to both sides.
Sauté Onion (1) rings until starting to caramelize, then season with Kosher Salt (to taste) and Cayenne Pepper (to taste). This step might take a while.
Meanwhile, grill the chicken halfway.
Juice the Lemon (1/2). You will need 1 tablespoon.
Drizzle with 1/2 tablespoon lemon juice, turn chicken, then repeat on the other side.
Cook until chicken is medium well, remove from grill, let rest in a warm place for 3-4 minutes to let the carry-over heat finish the cooking process and redistribute the juices.
To serve, top with the onions and serve with salads or sides of your choice.