Wash hands with soap and water.
Gently rub basil leaves and tomatoes under cold running water.
For marinade, place tomatoes, olive oil, garlic, vinegar, salt and basil leaves in a blender. Cover and process until well blended.
Place chicken breasts in a shallow dish. Cover with marinade. Cover dish. Refrigerate about 1 hour, turning occasionally. Do not rinse raw poultry.
Wash hands with soap and water.
Place chicken on an oiled grill rack over medium heat. Do not reuse marinades used on raw foods.
Wash hands with soap and water after handling raw chicken.
Grill chicken 4-6 minutes on each side until internal temperature reaches 165°Fon food thermometer.