Mix together the fish marinade ingredients.
Add in the slices of fish, making sure they are evenly coated in the marinade. Marinate for 20 minutes.
Heat up cooking oil inalag pot over medium high heat. Add in the dried chilies, leeks, garlic, ginger, and green onions. Cook down for 5 minutes.
Add in the pickled mustard greens. Cook for 5 more minutes.
Stir in the bean paste, making sure that everything is evenly coated in it. Deglaze with the cooking wine.
Pour in the chicken stock, sugar, salt, and white pepper. Bring to a boil, then reduce heat to medium and simmer uncovered for 15 minutes.
Add in the fish. Simmer another minute or two, until the fish is cooked through.
In a separate small sauté pan, heat up cooking oil over medium heat. Add in the peppercorns and bean paste.
Cook until the peppercorns start to darken.
Drizzle some of the oil over the fish.