Step 1Arrange tomato slices attractively in overlapping pattern on two dinner plates. Arrange onion rings over slices, dividing evenly.
Step 2Cook oil, vinegar, salt and pepper in small skillet over medium heat until simmering, about 1 minute.
Step 3Stir warm dressing and drizzle over salad, dividing evenly on 2 plates. Sprinkle with cheese. Garnish each with 5 basil leaves. Serve immediately while vinaigrette is still warm.