Set aside several whole basil leaves for garnish. Using sharp knife, chop remaining basil leaves. In medium bowl, mix chopped basil, oil, pepper and vinegar. Add cheese to oil mixture, tossing gently til well coated. Cover and chill for at least 1 hour before serving or up to 5 days.
Transfer cheese mixture to serving bow.. If desired, stir in tomatoes. Garnish with reserved whole basil leaves. If desired, serve with flatbread or baguette slices. Makes 14 servings.