Watermelon and tomato salad with fresh herbs

4 cups bite-sized watermelon cubes (drained of any standing juice);

2 cups seeded and diced tomatoes;

1⁄2 small Vidalia or other sweet onion, halved lengthwise and cut into thin strips (about 1⁄2 cup);

3⁄4 cup ricotta salata cheese cut into very small cubes;

3 tablespoons extravirgin olive oil;

2 tablespoons fresh lime juice;

2 tablespoons chopped fresh mint;

2 tablespoons chopped flat-leaf parsley;

2 tablespoons chopped fresh basil;

1 teaspoon kosher salt;

1⁄2 teaspoon black pepper;

1 teaspoon sugar.

Gently stir together the watermelon, tomato, onion, cheese, oil, and lime juice in a large bowl. Cover and refrigerate until chilled, at least 1 hour. (Normally tomatoes are not good when chilled, but it works here.)
Add the mint, parsley, basil, salt, pepper, and sugar and serve right away.
What else works? You can use cubes of fresh pineapple or peaches in place of the watermelon, particularly those little hard green peaches that never seem to ripen.