1. Place pork chop on plate and freeze until very firm, about 20 minutes. While pork freezes, prepare gai lan. Remove leaves, small stems, and florets from stalks; slice leaves crosswise into 1½-inch strips (any florets and stems can go into pile with leaves); and cut stalks on bias into ¼-inch-thick pieces. Set aside.

2. Stir 1 tablespoon water and baking soda together in medium bowl. When pork is firm, use sharp knife to shave pork crosswise as thin as possible. (Slices needn’t be perfectly intact.) Transfer to bowl with baking soda mixture and toss until well coated. Add 1 teaspoon Shaoxing wine and 2 teaspoons soy sauce and toss to combine. Set aside.

3. Bring 4 quarts water to boil in large pot. While water heats, stir cornstarch and ¼ cup water together in small bowl. Stir oyster sauce, fish sauce, sugar, sesame oil, white pepper, and remaining 1 teaspoon soy sauce together in separate bowl.

4. Add mushrooms to boiling water and cook until tender and pliant, about 30 seconds. Using spider skimmer or slotted spoon, transfer mushrooms to bowl. Return water to boil. Add bell pepper and cook until crisp-tender, about 30 seconds. Using spider skimmer, transfer bell pepper to second bowl. Return water to boil. Add gai lan and cook until stems are crisp-tender, about 1 minute. Using spider skimmer, transfer gai lan to bowl with bell pepper. (Vegetables can be blanched 24 hours ahead.)

5. Return water to boil. Add noodles and cook, stirring often, until almost tender (center of noodles should be firm with slight opaque dot), 45 to 90 seconds. Drain noodles in colander and rinse under cold running water, tossing with tongs, until cool to touch, about 1 minute. Drain noodles very well.

6. Line large serving plate with triple layer of paper towels. Add oil to wok until it measures about ¾ inch deep and heat over medium-high heat to 350 degrees. (If using skillet, add oil until it measures ¼ inch deep, about 1¼ cups.) Carefully lower noodles into oil (oil will bubble vigorously; do not use colander to tip noodles into oil). Using spatula, spread noodles into even layer. Fry until outer 2 inches of noodle disk are crisp and lightly browned, 3 to 5 minutes, occasionally rotating disk for even crisping. Using 2 thin spatulas, transfer noodle disk to prepared plate. Carefully pour off oil from wok into bowl. Reserve 1 tablespoon oil (reserve remaining oil for other use) and wipe out wok. Leaving noodle disk on plate, remove and discard paper towels. Pour off any excess water from cooked bell pepper and gai lan.

7. Heat now-empty wok over medium heat until smoking. Add 1½ teaspoons reserved oil, scallions, and ginger and cook, stirring constantly, until fragrant, about 15 seconds. Increase heat to high and add pork. Cook, stirring constantly, until pork is no longer pink, 1 to 2 minutes. Transfer to bowl with bell pepper and gai lan.

8. Add remaining 1½ teaspoons reserved oil and mushrooms to now-empty wok and cook, stirring constantly, until mushrooms have shrunken slightly, about 2 minutes. Add remaining 1 tablespoon Shaoxing wine and cook, stirring constantly, until no liquid remains in wok, about 15 seconds. Add oyster sauce mixture and cook, stirring constantly, until bubbling, about 15 seconds.

9. Add chicken broth, pork, and vegetables and bring to simmer. Stir cornstarch mixture to recombine; add to wok; and cook, stirring constantly, until sauce is thick and translucent, about 1 minute. Spoon pork and vegetables over noodles and serve immediately. At the table, use large spoon to cut through noodles; scoop noodles and stir-fry onto individual serving plates.