How to make it
Soak mushrooms in warm water to cover until softened, about 15 minutes; drain. Trim and discard stems. Coarsely chop caps
Combine sauce ingredients in a bowl; set aside.
Place a wok over high heat until hot. Add 2 tbsp oil, swirling to coat sides. Add shallot; cook, stirring, until fragrant, about 10 seconds.
Add duck; stir-fry for 1 minute. Add mushrooms, ginger, pineapple, water chestnuts, cilantro, and green onion; stir-fry for 1 minute. Add sauce; cook, stirring, until sauce boils and thickens
To eat, spread a small amount of Lee Kum Kee Hoisin Sauce on a lettuce cup, spoon in some duck mixture, wrap up in lettuce cup, and eat out of hand.