In a small mixing bowl, combine soy sauce, dark soy sauce, sesame oil, water (or vegetable stock), and sugar. Stir well until the sugar dissolves completely, forming a smooth, glossy sauce. Set aside.
Boil the noodles according to the package instructions until just tender. Drain thoroughly, then rinse briefly under cold water to stop the cooking process and prevent sticking. Set aside.
Heat a generous drizzle of oil in a large wok or skillet over medium-high heat. Once the oil is hot and shimmering, add sliced garlic, the white parts of the green onions, and chopped red chili. Stir-fry for 2–3 minutes until fragrant and lightly golden, releasing the aromatics’ rich flavor.
Add the cooked noodles to the wok, followed by the prepared soy sauce mixture. Toss thoroughly to ensure every strand is evenly coated in the dark, savory sauce. Stir-fry for 2–3 minutes, allowing the noodles to absorb the flavor.
Turn the heat up to high and toss in the bean sprouts. Stir-fry quickly for another 2–3 minutes until they are slightly wilted but still crisp. Add the remaining green onion pieces and sauté for 1–2 more minutes, ensuring a balanced mix of textures and color.
Serve immediately while hot, letting the glossy, aromatic noodles shine with their deep umami flavor and slight hint of spice.