In a large bowl, stir together shrimp, cumin, lime juice, cilantro, garlic, and 2 tablespoons oil; season with salt and pepper. Toss until combined, then let marinate in the refrigerator for 10 minutes
In a large skillet over medium heat, heat remaining tablespoon of oil. Add shrimp and marinade cook until pink, about 2 minutes per side.
To assemble wraps: Add shrimp and avocado to lettuce leaves, drizzle with sour cream, and garnish with cilantro. Serve with lime wedges.