2 cups diced orange-fleshed melon, such as Charentais (1/4- to 1/2-in. cubes)
1 cup diced cucumber (1/4- to 1/2-in. cubes)
1/2 cup finely chopped red onion
1 serrano chile, stemmed, halved, and sliced
1/2 cup roughly chopped cilantro
3 tablespoons lime juice
1 tablespoon vegetable oil
1 teaspoon kosher salt
Mix all ingredients together in a medium bowl.
Make ahead: Up to 1 day, covered and chilled.
Note: Nutritional analysis is per 1/2-cup serving.