Mix the marinade ingredients in a bowl, coat the duck, cover, and refrigerate for 20 minutes.
Soak 12 wooden bamboo skewers in cold water.
Mix 600g plain flour, strong flour, and salt in a bowl, then add 400ml boiling water.
Add 150ml cold water and knead the mixture into a smooth dough.
Heat rapeseed oil, sesame oil, peppers, and salt in a small pan, then remove from heat.
Roll out dough, spread with seasoned oil, scatter spring onions and remaining flour over it.
Cut dough into eight connected sections, fold each to the centre, roll out, and repeat folding.
Roll dough into a rectangle, then a 10cm wide cylinder, and divide into 12 small circles.
Cook pancakes in a pan with rapeseed oil until golden-brown and keep warm in the oven.
Heat a griddle pan, thread marinated duck onto skewers, and mix with 2 tablespoons oil.
Griddle the skewers for 1 minute per side until they no longer stick to the pan.
Assemble by spreading hoisin on pancakes and topping with lettuce, duck, sauces, and cucumber.