This is so simple and a nice addition to any backyard BBQ.
Watermelon Salad
1 seedless watermelon
½ red onion, sliced thin
Kosher salt to taste
¼ cup extra virgin olive oil
¼ cup lime juice
3 tablespoons honey
2 tablespoons cilantro

Do this-
Cube watermelon into bite size pieces and toss with onions and salt. Combine olive oil, lime juice, honey and cilantro. Pour over watermelon and toss