1. Whisk together the vinegar and oil and season to taste with salt and pepper. Lay the tomato rounds on the bottom of a large platter.
2. Season with salt and pepper and dress lightly with some of the dressing. Scatter the cucumbers on top of the tomatoes, season with salt and pepper and dress those as well.
3. Scatter the cucumbers on top of the tomatoes, season with salt and pepper. Finish with the red onion pieces, season with salt and pepper and drizzle more dressing on top.
4. Garnish all over with cilantro sprigs.
Recipe courtesy of Rocco DiSpirito, copyright 2002.