Heat the toasted sesame oil in a large skillet over medium-high heat.
Add the ground chicken to the skillet, breaking it into small crumbles with a spatula until it is fully browned.
Stir in the minced ginger and garlic, sautéing for about 1 minute until fragrant.
Add the diced shiitake mushrooms, chopped water chestnuts, and diced red bell pepper to the chicken mixture.
Cook for 3-4 minutes, stirring occasionally, until the vegetables are tender but still retain a slight bite.
Pour in the coconut aminos and rice vinegar, tossing the mixture thoroughly to ensure everything is evenly coated.
Season the mixture with sea salt and black pepper, then remove the skillet from the heat.
Carefully wash and pat dry the butter lettuce leaves, then arrange them on a serving plate.
Spoon the warm chicken mixture into the center of each lettuce leaf.
Garnish with thinly sliced scallions and toasted almond slices for extra texture.