In a bowl, add the sliced duck pieces, half of the crushed Sichuan peppercorns, salt and mix well.
Cook the Hokkien noodles as per packet instructions and keep aside.
Add 1 tbsp sesame oil to the wok and heat; when the wok is smoking hot, add the sliced duck pieces and stir fry on high heat for a minute. Then lower heat and add half of the julienned ginger and cook covered till the duck pieces are cooked and tender. Remove the duck pieces along with the juices if any and keep aside.
Heat the wok again (if there is any liquid residue from the duck meat, allow to dry out) and add the remaining sesame oil.
When smoking hot, add the onions and shitake mushrooms. Stir fry for 30 seconds and then add the bell peppers. Mix and return the duck pieces to the wok.
Also add the remaining Sichuan peppercorns, hoisin sauce, chilli sauce and rice wine vinegar.
Toss well and then add the cooked Hokkien noodles and the baby bok choy leaves. Toss well to combine, taste and season with salt if necessary.
Remove from heat and serve.