Combine 2 tablespoons vinegar and 1 teaspoon oil in a large zip-top plastic bag; add chicken to bag. Seal and marinate in refrigerator 10 minutes. Remove chicken from bag, and discard marinade. Place chicken on grill rack coated with cooking spray; cook 4 minutes on each side or until chicken is done. Cut into 1/4-inch-wide strips.
Heat 1 teaspoon oil in a large sauce-pan over medium heat. Add the potato; cook 10 minutes or until tender, stirring constantly. Stir in onion and next 5 ingredients (onion through garlic); cook 5 minutes, stirring occasionally. Stir in tomato and next 4 ingredients (tomato through pepper). Cook 3 minutes; remove from heat.
Place 1/2 cup vinegar in small saucepan. Bring to a boil; cook until reduced to 1/4 cup (about 3 minutes).
Spoon 1 cup cooked vegetables onto each of 4 plates. Arrange 1 sliced chicken breast half over vegetables. Drizzle 1 tablespoon reduced vinegar over each serving.