If using refrigerated fresh flat noodles, separate them gently by hand; if frozen, thaw according to package and loosen with a splash (1–2 tbsp) of warm water. Pat dry if very wet.

Peel and thinly slice the yellow onion into 1/8–1/4-inch slices. Trim and cut green onions into 1-inch pieces, keeping whites and greens separate. Rinse and drain bean sprouts thoroughly.

Crack eggs into a bowl and beat lightly with a pinch of salt.

Mix the sauce: in a small bowl combine light soy sauce, dark soy sauce, oyster sauce, sesame oil, sugar, curry powder, white pepper and 2 tbsp water. Stir until sugar dissolves.

Make the sweet & sour sauce: whisk together rice vinegar, ketchup, brown sugar, pineapple juice, soy sauce, and red pepper flakes (if using). In a separate tiny bowl mix cornstarch with 1 tbsp water to make a slurry and set aside.

Cook Noodles & Vegetables

Heat wok/pan

Place a large wok or heavy skillet over high heat until very hot (about 1–2 minutes). Add 1 tablespoon neutral oil and swirl to coat.

Scramble eggs: pour beaten eggs into the hot oil, let set briefly, then scramble into large soft curds (30–45 seconds). Remove eggs to a plate and set aside.

Add remaining 1 tablespoon oil to the wok. Add minced garlic and the white parts of the green onions and stir-fry 10–15 seconds until fragrant (do not burn).

Add sliced yellow onion and stir-fry 1–2 minutes until starting to soften and edges are translucent.

Add fresh noodles to the wok. Use tongs or spatula to gently toss and separate noodles. Stir-fry 1–2 minutes to heat through. If noodles are sticking, splash up to 1–2 tablespoons water to help loosen.

Pour the prepared sauce evenly over the noodles. Toss vigorously to coat noodles and distribute color and curry flavor, 1–2 minutes. Taste and add up to 1/4 tsp salt or extra soy if needed.

Return scrambled eggs to the wok and add bean sprouts. Toss everything together for 30–45 seconds until bean sprouts are just wilted but still crisp and eggs are warmed through.

Stir in green onion greens, give a final toss, then turn off heat and drizzle with sesame oil (if not already used in sauce) and adjust seasoning.

Finish & Sweet-Sour Sauce

Transfer the Yellow Noodle to a serving platter. Garnish with extra green onions if desired.

Finish the sweet & sour sauce: heat a small saucepan over medium-low heat and pour in the prepared sweet & sour mixture. Bring to a gentle simmer and whisk in the cornstarch slurry. Cook 30–60 seconds until slightly thickened. Remove from heat and let cool slightly before serving on the side.

Serve immediately while hot, with the sweet & sour sauce on the side for dipping or drizzling.