Combine all ingredients except for ice and chicken in a saucepot. Bring to a simmer. Turn off heat and stir to dissolve salt and sugar.
Transfer to large container and stir in ice. Add chicken and let brine for four hours.
Preheat a gas or wood-fired grill (or grill pan). Preheat oven to 400 degrees Fahrenheit. Remove chicken from the brine, pat dry. Grill chicken until browned on all sides. Finish cooking chicken in hot oven.