1. Combine first 6 ingredients in a large bowl. Add shrimp; toss to coat. In a separate bowl, toss together lettuce, cilantro, and lime juice; cover and chill.
2. Heat a cast-iron grill pan or skillet over medium-high heat. Coat pan with cooking spray; add shrimp, and cook 3 to 4 minutes per side or until shrimp are done.
3. Warm tortillas according to package directions.
4. Divide shrimp evenly among tortillas. Top each tortilla with 1/4 cup lettuce mixture, 1 tablespoon diced tomato, 1 tablespoon tomatillo salsa, and 1 tablespoon sour cream; fold tortillas in half.