Add water chestnuts and mushrooms in a food processor and pulse for about 15-20 seconds until 1/4 inch in diameter or smaller. Set aside. Rinse our your food processor.
Chop your chicken breast into 2-3 inch cubes and place in the food processor. Chop until you have small pieces about 1/4 inch and smaller. Set aside.
In a bowl mix hoisin sauce, soy sauce, garlic, ginger, rice wine vinegar, sesame oil, and sriracha. Set aside.
In a wok at high heat, add 2 tbsp of peanut oil. Add your chicken and brown for about 2-3 minutes minutes, add about half the hoisin mixture and cook for about 2-3 minutes until no longer pink. You may need to drain excess water at this point.
Add your water chestnut and mushroom mix, along with the remaining hoisin sauce mixture. Stir in along with some chopped green onions.
For the Teriyaki Sauce
In the same wok, add soy sauce, hoisin sauce, agave nectar, water, garlic, ginger and sriracha. Let this simmer for about 5 minutes, stirring occasionally. It wont be thick like a traditional teriyaki sauce, but its super tasty!
Pull off a leaf of the butter lettuce, spoon in the chicken filling, add some crunchy chow mein noodles, and pour a couple spoonfuls of the teriyaki sauce. Enjoy!