Combine all the ingredients for the hoisin sauce together in a small bowl and mix well.
Set aside.
Heat a cast-iron skillet on med-hi heat.
When hot, add the ground chicken and sprinkle with salt and pepper to your liking.
As you cook and stir, break up any large chunks that are sticking together.
Cook until browned or until all chicken is fully cooked.
Add the onions and cook until fragrant, 2-3 minutes.
Whisk the hoisin sauce once more, making sure it’s mixed well, and then pour over chicken.
Add chopped chestnuts and green onions.
Cook for 2-3 minutes more.
Scoop chicken mixture onto lettuce leaves and top with additional green onions, if desired.
Serve and enjoy!
*Keep washed lettuce in a large ziplock with a folded paper towel to maintain freshness.