While corn and tomatoes are at their peak later in the summer, you can enjoy this simple salad all season long. White miso--the kind that's lowest in sodium--adds a powerful umami punch to the mix, enhancing the meaty flavor that tomatoes and Parmigiano-Reggiano cheese provide. Salting the tomatoes and letting them stand draws out their juices so they'll meld with the dressing when you combine all the components.
2 large ripe heirloom tomatoes, cored and cut into 1-in. dice, or 1 diced heirloom tomato and 1 cup halved cherry tomatoes