1/2 cup broth
1 tablespoon extra-virgin olive oil
3 tablespoons balsamic vinegar
2 teaspoons Dijon mustard
1/2 minced garlic clove or 1 to 2 teaspoons garlic powder
2 teaspoons sugar
1 teaspoon crushed thyme
1/4 teaspoon black pepper
2 pounds chicken breasts, boned and skinned (8 halves)
Place all ingredients except chicken breasts in a jar with a tight-fitting lid and shake well. Rinse chicken breasts and pat dry with paper towels.
Place chicken breasts and marinade in a locking plastic bag, making sure the chicken is coated well (using a bag saves on cleanup, but a shallow dish works just as well).
Marinate the chicken in the refrigerator for several hours, turning occasionally.
Prepare the outdoor grill or preheat the broiler or a stovetop grill pan. Grill the chicken or place under the broiler for about 10 minutes per side. Cooking time will vary depending on the thickness of the chicken.
The chicken is done when the internal temperature reaches 165 degrees using an instant-read thermometer. Discard the marinade.