How to Make It
Place first 4 ingredients in a 7-qt. slow cooker. Add chicken, 1/3 cup vinegar, and 1/2 cup water. Sprinkle chicken with salt and black pepper. Cover and cook on LOW 5 to 6 hours or until meat easily pulls from bone. Remove meat from bones; discard skin and bones. Shred meat. Pour cooking liquid through a fine wire-mesh strainer into a measuring cup; discard solids. Let cooking liquid stand 10 minutes. Skim fat, and reserve 1/3 cup cooking liquid. Toss remaining cooking liquid with chicken.
Whisk together mayonnaise, red pepper, reserved 1/3 cup cooking liquid, and remaining 1 1/2 tsp. vinegar; season with salt and pepper. Spoon chicken into lettuce leaves; drizzle with sauce. Add toppings. Serve immediately.