01 - Preheat your grill to medium-high heat (about 400°F).
02 - Brush both sides of each watermelon wedge lightly with olive oil. Sprinkle watermelon evenly with sea salt and black pepper.
03 - Place watermelon wedges on the grill and cook for 2-3 minutes per side, until grill marks appear and the fruit is slightly caramelized.
04 - Remove watermelon from the grill and transfer to a serving platter. Immediately drizzle lime juice over the grilled watermelon, then sprinkle with lime zest and chopped cilantro. Add chili flakes if desired.
05 - Serve immediately as a side or light appetizer.