To make the tomato-basil salsa: In a medium bowl, comvine the tomatoes, scallions, basil, oil, vinegar, peppers (if using) and sugar (if using). Cover and refrigerate while preparing the chicken.
To make the chicken and marinade: Combine the tomato juice, garlic and oil in a shallow bowl large enough to hold the chicken. Place the chicken in the bowl and marinate for 15 minutes. Remove the chicken from the marinade and discard the marinade.
While the chicken is marinating, coat an unheated grill rack with no-stick spray. Light the grill according to the manufacturer's directions. Place the rack on the grill.
Place the chicken on the rack and grill 4" to 6" from the heat for 6-8 minutes, or until cooked through, turning once. Serve topped with salsa.