Prepare all your ingredients. Mince the garlic, chop the red bell pepper and onion, and drain the water chestnuts.
In your slow cooker, combine the ground chicken, minced garlic, chopped bell pepper, onion, hoisin sauce, soy sauce, salt, and pepper. Mix everything together until combined.
Stir in the sliced water chestnuts, ensuring they are evenly distributed throughout the mixture.
Cover the slow cooker and cook on low for 4 to 6 hours, or until the chicken is fully cooked and tender. If you're in a rush, you can also cook it on high for 2 to 3 hours.
While the chicken is cooking, prepare your rice according to package instructions. Set aside when done.
Once the chicken mixture is ready, serve it in lettuce leaves. You can add a scoop of rice if desired, and top with sliced green onions for garnish.
For an extra flavor kick, drizzle a bit of rice vinegar and sesame oil over the wraps before serving.