In a medium skillet, heat bell pepper, green onions and water chestnuts over medium high heat, stirring occasionally, cook for 3 minutes.
Add shrimp and marinade and cook 3 more minutes, or until shrimp are pink and cooked through.
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.