Marinate the pork in the soy sauce, oyster daus, shaoxing wine, and ginger juice for at least 15 minutes.
Prepare the sweet and sour sauce by whisking together the water, rice vinegar ketchup, sugar, potato starch and salt and set aside.
Cut all the vegetables and have them ready. Prepare a paper towel lined wire rack.
Add 1-inch of oil to a heavy bottomed pot and heat to 340 degrees F (170 C).
Whisk together the flour, 2 tablespoons of potato starch, and baking powder.
In a liquid measuring cup, whisk the egg until the yolk and white are evenly mixed. Add enough cold water to make a total of ⅔ cup minus 2 tablespoons liquid.
Add the liquid to the flour and stir until there are no large lumps remaining, but do not overmix.
Fry the pork by coating each piece in batter and adding to the pre-heated oil. Fry until each piece is golden brown and then transfer to the prepared rack.
Fry the vegetables until bright in color and just barely cooked and transfer them to the prepared rack.
To finish give the sauce a stir to combine any starch that has settled to the bottom and pour it into a clean frying pan over high heat. Bring the mixture to a boil and cook until it is thick. Add the pork and vegetables and toss to coat evenly with sauce.