How to Make It
Preheat grill to medium-high (400°F to 450°F).
Whisk together honey, lime juice, salt, and 1 teaspoon of the Tajín in a small bowl. Brush watermelon wedges evenly on both sides with mixture.
Place watermelon on oiled grates; grill, uncovered, until grill marks appear, about 2 minutes per side. Remove from grill; let cool slightly, about 5 minutes.
Arrange watermelon wedges on a serving platter; sprinkle with remaining 1 teaspoon Tajín. Sprinkle with Cotija and cilantro. Serve with lime wedges.