Preheat a gas grill to high heat. Place the husked corn directly on the grates and grill for about 10 minutes, turning every few minutes, until evenly charred. Remove from the grill and cut the kernels off the cob.
Add the lemon halves to the grill, cut-side down. Cook for 3–4 minutes, until lightly charred.
In a large bowl, combine the grilled corn kernels, cubed watermelon, cucumber pieces, feta cubes, and chopped fresh herbs.
In a small bowl, squeeze the juice from 1 charred lemon half. Whisk in the olive oil, kosher salt, and black pepper. Taste and adjust seasoning as needed.
Pour the dressing over the salad and toss until well combined. Serve immediately.
Notes
Feta: Use feta from a block in brine for the best flavor and cube it yourself instead of buying pre-crumbled.
Lemon: Grill an extra lemon if you’d like wedges for serving at the table.
Storage & Make Ahead:
Best enjoyed fresh.
Prep ingredients up to 1 day ahead; store separately.
Grill corn and lemon in advance, then assemble before serving.