Heirloom tomatoes are grown from seeds that have been saved from year to year. Their flavor is worlds away from the sort typically found in the produce department. The colors and shapes can vary greatly from one variety to another. So can the flavor. Choose several different kinds to create the prettiest summer salad. Taste and adjust the vinegar, salt, and pepper amounts to best highlight your unique tomatoes.
Arrange the tomatoes on a large serving plate. In a 2-cup measuring cup, whisk together the remaining ingredients. Pour the olive oil mixture over the tomato slices. Garnish, if desired.