In a medium bowl, toss the pork with 1 Tbs. of the soy sauce, 1 Tbs. of the sherry, the cornstarch, and 1/4 tsp. of the salt. Refrigerate for at least 15 min. and up to 1 hour. Bring 2 quarts of water to a boil in a large pot. Add 2 Tbs. of the salt and cook the noodles, stirring occasionally, until just tender, about 3 min. Drain in a colander and run under cold water until the noodles cool to about room temperature. Turn the noodles out onto a baking sheet lined with paper towels to dry. Heat 1-1/2 Tbs. of the oil in a 12-inch nonstick skillet over medium heat. Add the noodles and cook, tossing occasionally, until golden and slightly crisp, about 6 min. Meanwhile, replace the damp paper towels on the baking sheet with dry ones. When golden, transfer the noodles to the dry towels. Heat 1-1/2 Tbs. of the oil in the nonstick skillet over medium-high heat until shimmering hot. Add the pork and cook, tossing often, until browned and just cooked through, 2 to 3 min. Transfer to a plate or bowl. Pour the remaining 2 Tbs. oil into the skillet and then add the scallions, mushrooms, and 1/4 tsp. of the salt. Cook, stirring occasionally, until browned, 3 to 4 min. Add the ginger, garlic, and pepper flakes and cook, stirring, until fragrant, 30 to 60 seconds. Add the cabbage, bean sprouts, and the remaining 1/2 tsp. salt. Cook, stirring often, until the cabbage just starts to soften, 1 to 2 min. Add the noodles and pork to the pan and cook, stirring, until heated through, 1 to 2 min. Add the remaining 1-1/2 Tbs. soy sauce, the remaining 1 Tbs. sherry, and the sesame oil and cook, tossing the ingredients, for 1 min. more. Serve immediately. Add more soy sauce to taste or pass the soy sauce at the table.