Rinse dried shiitake mushrooms under running water; Soak them in water for 3 hours; Remove and drain them; Discard the stems with a pair of kitchen scissors; Slice the remaining with a vegetable knife.
Rinse salted mustard greens under running water; Soak it in water for 10 minutes; Remove it; Squeeze and julienne it.
Rinse celery under running water; Drain it; Trim a bit off the bottom; Pull off the outer leaves and tough stalks; Discard any wilted leaves; Cut the remaining into sections; Rinse them under running water again; Drain them.
Rinse and drain red chili peppers; Slice off any stems; Bisect them lengthwise with a vegetable knife; Scrape off any seed; Julienne them.
Rinse, drain, peel and julienne ginger.
Rinse Bombay duck fishes under running water; Insert the knife into the anus near the tail of each, and draw the knife toward the head, splitting each to the base of the gills; Spread the abdominal cavity of each with fingers; Reach in and pull out the entrails; Rinse the cavity of each under running water; Cut off the head of each with the knife; Rinse each under running water again; Pat-dry each with kitchen paper.
Add seasonings to a mixing bowl; Mix.
Add 2 tbsp oil and the ginger into a wok; Stir-fry over a high heat till fragrant; Add the dried shiitake mushrooms, the red chili peppers, the salted mustard greens and the celery; Drizzle 1 tsp Shaoxing rice wine over them; Stir-fry them over a high heat for 2 minutes; Add the Bombay duck fishes and the seasonings; Bring to the boil over a high heat; Simmer it for 8 minutes; Turn off the heat; Arrange it on a serving plate; Ready to serve.