Although the recipe calls for roma tomatoes, the heirloom varieties were too pretty for me to pass up. That's what I love about this recipe, it's more of a suggestion than something set in stone.
Select the tomatoes and herbs you want to use. If you feel like adding in a layer of fresh mozzarella cheese between the toasts and tomatoes, do it. Want to stir crumbled feta in with the tomatoes? Why not? Just be sure to enjoy while the tomatoes are at their peak season, now! Here's the recipe.