In a medium bowl, combine lime juice, 2 tablespoons oil, 1 tablespoon soy sauce, ginger and garlic. Add shrimp and let marinate in refrigerator for 30 minutes.
In a medium skillet, heat 1 tablespoon oil over medium-high heat. Add bell pepper, green onions, and water chestnuts; cook, stirring occasionally, for 3 minutes. Add shrimp and marinade and cook 3 minutes, or until shrimp are pink. Stir in 1 tablespoon soy sauce.
Divide lettuce into leaves. Spoon about 1/4 cup mixture down center of 1 lettuce leaf. Fold bottom edge and sides up and over filling. Repeat with remaining lettuce leaves and shrimp filling.