To tenderize the pork chops, place them on a cutting board, uncovered, and, using the “tooth” side of a meat mallet, pound them 4 or 5 times on each side; then cut them into 3 or 4 pieces. In a medium bowl, whisk together 1 teaspoon of the cornstarch, the Shaoxing wine, soy sauce, five-spice powder, sesame oil and egg until well combined. Add the pork and toss to coat. Cover and marinate for at least 5 minutes on the counter, or refrigerate overnight. Line a platter with towels and place it near the stove. In a wok or skillet over high heat, heat the oil. To test if the oil is hot enough, place the end of a wooden spoon into the oil: Bubbles should immediately fizz around it. If the oil is smoking, it is too hot, so reduce the temperature. Add the remaining 2 tablespoons of cornstarch and the flour to the marinated pork and toss to lightly coat each piece. Working in batches to avoid overcrowding, carefully transfer the pork to the hot oil and fry until crisp, about 2 minutes per side. Transfer to the prepared platter and repeat with the remaining pork. In a large skillet over medium-high heat, whisk together the ketchup, hoisin sauce, Worcestershire sauce, water, five-spice powder, sugar, chili oil and salt and bring to a vigorous simmer, stirring frequently, until thick and sticky, about 5 minutes. Reduce the heat to medium, add the fried pork to the sauce and toss until well coated, about 2 minutes. Transfer the pork to a platter, sprinkle with the scallions and serve family-style, with rice on the side, if desired.