For the sauce, combine the salt, cornstarch, sugar, rice wine, vinegar, soy sauce, plum sauce and water in a measuring cup. Taste and adjust the flavors for pleasant tart-sweet-salty flavor. Set aside.

Trim and cut the pork into pieces the size of a cherry or small ice cube. Put into a bowl and add the rice wine, 1 ¼ teaspoons cornstarch, oyster sauce, and soy sauce. Set aside to marinate for 30 minutes. Meanwhile, prep the remaining ingredients, if you haven’t, and get a pot of rice going.

Heat about ¾-inch (2 cm) of oil in a wok, deep skillet or low saucepan to about 350F (175 to 180C). As that happens, add the egg to the pork to coat well. Put the cornstarch on a plate and dredge the pork. Let sit to get absorbed and set, about 3 or 4 minutes.

In batches, fry the pork for 2 to 3 minutes, until pale golden. Let drain on paper towel and/or a rack. To crisp the pork, raise the heat on the oil until very hot (about 375F / 190C). Slide all the fried pork cubes back into the oil and refry until a rich brown and crisp. Re-drain. (It’s a pain in the butt to pour the oil out and clean what you just fried in, so use a clean skillet or wok for the next step.)

Heat a large skillet or wok over high heat. Swirl in 2 teaspoons oil, then add the onion and pineapple. Fry for about 2 minutes, stirring and flipping, until the pineapple picks up some dark brown streaks. Add the ginger and pepper. Cook, stirring constantly, for 1 minute, until the peppers are crisp tender.

Add the tomato and pour in the sauce. Cook, stirring, for 30 to 45 seconds, until the sauce bubbles and thickens. Add the pork and stir to combine and coat. Transfer to a serving plate, garnish with the green onion and enjoy with lots of rice.