2 tablespoons minced red onion, rinsed and drained
2 teaspoons chopped seeded serrano pepper
2 tablespoons olive oil
1 teaspoon lime zest
1 tablespoon fresh lime juice
1/8 teaspoon kosher salt
1/8 teaspoon ground cumin
12 butter lettuce leaves
1/4 cup crumbled queso fresco
In a medium bowl, gently toss together shrimp, watermelon, avocado, cilantro, onion, serrano, oil, lime zest and juice, salt, and cumin. Arrange lettuce leaves on serving plates. Spoon shrimp mixture onto leaves, and sprinkle with queso fresco. Serve immediately.