Get out a large bowl.
Cut your watermelon in bite size pieces. Add it to the bowl.
Add sliced onions, basil,mint, and feta cheese to your bowl.
Drizzle the olive oil to coat salad and toss.
You can either drizzle the balsamic over the whole salad and toss it before you serve, or you can dish out the salad first and then drizzle the balsamic reduction over each plate. Either way will be yummy!