Arrange mozzarella slices in a single layer in shallow dish. In small bowl, whisk together olive oil, vinegar, 1 tablespoon lemon balm, sugar, salt, mustard and garlic. Drizzle ¼ cup vinaigrette over cheese, turning slices to coat evenly. Refrigerate remaining vinaigrette and cheese, covered, several hours.

To Serve: Let cheese and vinaigrette stand at room temperature 30 minutes. Slice tomatoes ¼-inch thick; arrange in large shallow serving dish, alternating red and yellow tomatoes and mozzarella. Drizzle with reserved vinaigrette; sprinkle with remaining lemon balm and basil chiffonade.

FoodE Tip: Chiffonade (shihf-uh-NAHD) is a French term that refers to thin strips or shreds of vegetables or herbs. Make basil chiffonade by layering four or five leaves, largest on bottom, and rolling tightly like a cigar. Thinly slice across the leaves while holding the roll tightly; separate into strips.