Preparation Combine shallots, vinegar, 1/2 teaspoon salt, and sugar in a small bowl. Gradually whisk in oil to blend. Set vinaigrette aside. Arrange tomatoes on a large platter. Sprinkle capers over; season with salt and pepper. Scatter basil on top. Whisk vinaigrette again; drizzle over salad.
Preparation Combine shallots, vinegar, 1/2 teaspoon salt, and sugar in a small bowl. Gradually whisk in oil to blend. Set vinaigrette aside. Arrange tomatoes on a large platter. Sprinkle capers over; season with salt and pepper. Scatter basil on top. Whisk vinaigrette again; drizzle over salad.