Tomato And Watermelon Salad With Feta Cheese

Name: Tomato And Watermelon Salad With Feta Cheese
Ingredients: 1/4 cup red wine vinegar; 1 teaspoon kosher salt; 1/4 teaspoon freshly ground black pepper; 1/2 cup extra-virgin olive oil; 1 small cucumber, peeled; 1/2 small red onion; 3 heirloom tomatoes (about 12 ounces total), cut into bite-size chunks; 3 1/2 cups peeled seeded bite-size watermelon chunks; 1 red bell pepper, cut into bite-size chunks; 7 ounces French feta cheese, cut into 1/2-inch cubes; 1 cup fresh mint leaves, thinly sliced