In a small bowl, soak shitake mushrooms in warm water for about 30 minutes or until softened. Drain and squeeze out liquid. Stem mushrooms and mince. Set aside.
In a bowl, combine chicken, one tablespoon of the soy sauce, Chinese cooking wine, and cornstarch. Marinate for about 10 to 15 minutes.
In a pan over medium heat, heat about 1 cup of oil until hot. Add noodles and deep-fry for about 10 to 15 seconds or until puffed up and color changes to white. Using a slotted spoon, remove from pan and drain on paper towels. Set aside.
In a small bowl, combine hoisin sauce, the remaining one tablespoon soy sauce, and rice vinegar. Whisk together until blended and set aside.
In a wide skillet over medium heat, heat about 1 tablespoon oil. Add garlic and ginger and cook, stirring regularly, until aromatic.
Add chicken and cook, breaking apart with the back of a spoon, until lightly browned.
Add water chestnuts and mushrooms. Continue to cook for about 2 to 3 minutes or until vegetables are tender-crisp.
Add hoisin sauce mixture and stir until chicken is well coated. Continue to cook for about 3 to 5 minutes or until sauce is absorbed and chicken is cooked through.
Add green onions and stir to combine. Remove from heat and transfer onto a serving platter.
To serve, spoon the chicken mixture into the center of the lettuce leaf and top with fried noodles.
Notes
You can grate the ginger to get all the flavor, but with peppery bits to bite into.