Prepare a charcoal grill with hot coals or heat a gas grill to high. Place oil, vinegar, garlic, rosemary and basil in a food processor; pulse until thoroughly blended. Remove 2 tablespoons; set aside. Place remaining marinade in a plastic food-storage bag; add pork and marinate at room temperature for 10 minutes. Toss reserved 2 tablespoons marinade with tomatoes; set aside.
To cook, remove pork from marinade, spray with nonstick cooking spray and place on grill. Grill for a total of 15 minutes, turning once, halfway through.
Meanwhile, bring 3 cups water to a boil; slowly add polenta and salt. Cook, stirring constantly, over medium heat until cooked, about 5 minutes. Remove from heat; stir in cream (or milk) and cheese. Serve pork with polenta and tomatoes. Makes 4 servings.