Bring 2 quarts water to a boil in a large saucepan over high. Place bean sprouts in a metal strainer; lower into boiling water, and blanch bean sprouts until crisp-tender, about 10 seconds. Remove strainer from water (do not remove water from heat), and rinse bean sprouts under cold water about 30 seconds to stop the cooking process. Drain well and set aside.

Add salt to water in saucepan and return to a boil over high. Add noodles and return to a boil over high. Boil, stirring often, until just under al dente, about 1 minute. Drain noodles thoroughly in a colander and rinse under cold water about 1 minute to stop the cooking process. Drain. Briefly rinse again and drain, lifting noodles to separate and dry the strands. Set aside.

Stir together stock, soy sauce, and sesame oil in a small bowl. Set aside.

Heat peanut oil in a wok over high until shimmering and fragrant; swirl to coat wok. Add ginger; cook, stirring constantly, until sizzling and starting to brown around edges, about 10 seconds. Add snow peas; cook, stirring constantly, until bright green, about 1 minute. Add water chestnuts; cook, stirring constantly, 30 seconds. Add bean sprouts; cook, stirring constantly, until wilted, about 1 minute.

Stir sauce and add to mixture in wok; bring to a boil over high. Add noodles to wok; cook, stirring constantly, until noodles absorb sauce, about 2 minutes. Remove and discard ginger. Season with additional soy sauce to taste. Transfer noodles to a platter and serve immediately.