Grilling watermelon adds a smoky note to the fruit and gives it a slightly meaty texture that matches well with shrimp. Cooking takes only a couple of minutes, so have both sets of skewers ready before you start. You'll need 12 flat metal skewers (12 in. long) or 18 skewers (8 in. long)--or use bamboo skewers of the same size, soaked in water for 30 minutes.
1/3 cup plus 1 1/2 tbsp. extra-virgin olive oil
Zest of 1 lime
3 tablespoons lime juice
1 tablespoon chopped fresh mint, plus 1/4 cup mint leaves, torn
1/2 teaspoon chopped fresh thyme leaves
1/4 to 1/2 tsp. red chile flakes
1 garlic clove, minced
1 1/4 teaspoons kosher salt
1/2 teaspoon pepper
1 pound jumbo peeled and deveined shrimp (21 to 26 per lb.), thawed if frozen
1/2 small seedless watermelon (about 2 lbs.)
How to Make It
In a medium bowl, whisk together 1/3 cup oil, the lime zest and juice, chopped mint, thyme, chile flakes, garlic, salt, and pepper. Pour half into a small bowl and set aside.
Add shrimp to remaining marinade mixture in medium bowl and chill, covered, about 1 hour.
Meanwhile, cut peel from watermelon, then cut fruit into chunks about 3/4 in. by 1 in. Heat a grill to very high (550° to 650°).
Thread watermelon onto six to nine skewers (8 to 12 in. long) so pieces lie flat. Brush on both sides with remaining 1 1/2 tbsp. oil. Thread shrimp onto six to nine more skewers, piercing each through its top and bottom to form a C (so shrimp lies flat).
Grill watermelon on one side only until grill marks appear, 1 minute. Transfer to a platter. Grill shrimp, turning once, just until pink, 1 1/2 to 2 minutes total; set on platter.
Drizzle skewers with reserved marinade and sprinkle with torn mint.