4 boneless skinless chicken breast halves, tender removed, 6 to 8 ounces each
2 quarts cold water
1/3 cup kosher salt, plus more for seasoning
1/4 cup sugar
Freshly ground black pepper
2 tablespoons olive oil
Place one chicken breast in a resealable plastic bag or between two pieces of plastic wrap. Using a meat pounder, rolling pin, or small skillet, pound chicken breast into an even thickness about 3/4-inches in height. Repeat with remaining 3 breasts.
To make the brine, in a medium bowl whisk together the the water, salt, and sugar until the solids are dissolved. Place the chicken breast slices in brine and refrigerate for 30 minutes.
Remove chicken breasts from brine, pat dry with paper towels, season to taste with salt and pepper, and brush lightly with olive oil. Place chicken over hot side of grill and cook until well browned, 3 to 5 minutes. Flip and continue to cook until second side is browned and chicken registers 160°F on an instant read thermometer inserted into the center of breast. If second side browns before it registers 150°F, move to cool side of grill, cover, and let cook until chicken reaches temperature. Remove chicken from grill, let rest for 5 to 10 minutes, then serve immediately.