Dice chicken breast, season with salt, pepper, and garlic powder, and cook over medium heat until lightly browned.
While chicken is cooking, separate lettuce leaves and rinse. Let dry in a colander or on some paper towels.
Add bamboo shoots, water chestnuts, red onion, garlic, and mixed nuts, and stir.
When onions are translucent, add soy sauce, crushed pineapple, and peanut sauce. Stir until sauce is warm.
Put a scoop of chicken mixture into lettuce leaf, wrap, and eat.