01 - Preheat grill to medium-high heat (400°F).
02 - Brush both sides of each watermelon wedge lightly with olive oil.
03 - Sprinkle watermelon evenly with sea salt and black pepper.
04 - Place watermelon wedges on the grill and cook for 2–3 minutes per side, until grill marks appear and the fruit is slightly caramelized.
05 - 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.
06 - Add chili flakes if desired for extra heat.
07 - Serve immediately as a side or light appetizer.