Prep the watermelon: Cut into bite-size cubes. Chill if you can—cold watermelon tastes best here.
Slice the cucumber: Halve lengthwise, then slice into thin half-moons. If seeds are large, scoop them out first.
Soften the onion: Thinly slice red onion or shallot.
Rinse under cold water and pat dry to mellow the sharpness.
Make the dressing: In a small bowl, whisk together the juice of 1 lime, 2–3 tablespoons olive oil, a small drizzle of honey, a pinch of salt, and black pepper. Add a pinch of red pepper flakes if you like a little heat.
Chop the herbs: Roughly chop mint and basil (or parsley). Keep them a bit chunky for bursts of flavor.
Assemble: In a large bowl, gently toss watermelon, cucumber, and onion with the dressing.
Add herbs and toss again.
Add feta: Crumble feta over the top and fold in gently. You want some big chunks to stay intact.
Finish: Taste and adjust. Add a pinch more salt, extra lime, or a drizzle of olive oil as needed.
Sprinkle nuts or seeds on top if using.
Serve: Enjoy right away, cold. It’s best within an hour of mixing.