Heat the vegetable oil in a large skillet over medium heat. Add the minced garlic and ginger, sauté for about 1 minute until fragrant.
Add the diced onion and bell pepper to the skillet, cooking until softened, about 3-4 minutes.
Increase the heat to medium-high and add the ground chicken. Cook until the chicken is browned and cooked through, breaking it apart with a wooden spoon, about 5-7 minutes.
Stir in the diced water chestnuts, soy sauce, hoisin sauce, and sesame oil. Mix well to combine and season with salt and pepper to taste. Cook for an additional 2 minutes until heated through.
Remove the skillet from the heat and let the mixture cool slightly.
Carefully separate the lettuce leaves from the head, rinsing them under cold water and patting them dry.
Spoon the chicken mixture into each lettuce leaf, topping with optional garnishes such as chopped green onions, peanuts, or cilantro.
Serve immediately and enjoy your Chicken Lettuce Wraps!