To a large plastic container with lid, add the dark soy sauce, oyster sauce, Shaoxing wine, water, and baking soda and stir until well combined. Add the pork strips and combine until they’re completely coated with the liquid and it’s absorbed.
In a small bowl, stir the sesame oil, white pepper and cornstarch together, add it the pork, combine well until thoroughly mixed through, pop the lid on, and marinate for 30 minutes. (Note: if you’re in a hot climate with no air-con, refrigerate the pork, however, it should be removed and reach room temperature before searing.)
While the pork is marinating, prep the rest of the Stroganoff ingredients: slice the onions and mushrooms and set aside; in a small bowl or jar, combine 1 tsp light soy sauce, 1 tbsp quality fish sauce, 1 tbsp tomato sauce, and 1 tsp Worcestershire sauce, and set aside; and ready the other ingredients.
When the pork is at room temperature, heat a wok over high until hot, pour 2 tablespoons soybean oil around the rim to coat the entire surface. Using tongs, transfer the pork to the wok, sear one side until opaque, then turn to sear the other side until opaque, all of which should take a minute, no more. Transfer the pork to a clean bowl and set aside. (Note: do the pork in two batches if needed.)
To the same wok, add a tablespoon of soybean oil and when hot, stir-fry the onions until translucent, then set aside.
Add another tablespoon of soybean oil, heat until hot, add the mushrooms and stir-fry on high for a minute or two until they start to brown, add the mixture of soy sauce, fish sauce, tomato sauce, and Worcestershire sauce, combine and continue to stir-fry for another minute.
Add the pork, combine well, and stir-fry continuously for 30 seconds, then return the onions, combine and stir-fry for another 30 seconds, then turn the heat down to medium.
Add the sour cream and cream, allspice, smoky paprika and wholegrain mustard, stir to combine well, then simmer for ten minutes or so until the sauce thickens and spices meld together. Taste and adjust the seasoning, adding the salt and white pepper if needed.
When the sauce is thick and creamy and rich and aromatic, plate individually with rice or noodles, garnish with fresh dill, and serve with dishes of gherkins and additional sour cream.