Lightly cut one side of each turkey breast in diamond pattern with knife. For marinade, blend 1/4 cup Wish-Bone Light® Italian Dressing with wine; pour over turkey breasts. Cover and marinate in refrigerator, turning occasionally, up to 3 hours.
Slice onion, root end down (leaving the root on) into 3/8-inch slices. Slice potato lengthwise into 3/8-inch slices, then halve slices lengthwise. Slice peppers lengthwise into quarters, then slice diagonally into eighths.
Remove turkey from marinade, discarding marinade. Grill or broil turkey and vegetables, turning once and brushing occasionally with remaining 1/2 cup Dressing, 10 minutes or until turkey and vegetables are tender. Garnish, if desired, with fresh cilantro.