Prep the beef: Freeze the steak for 15 minutes to firm it up. Slice thinly against the grain. Toss with soy sauce, cornstarch, and oil. Set aside while you prep everything else.

Cook the noodles: Boil according to package directions until just shy of tender. Drain and rinse briefly if using wheat noodles to stop the cooking. Toss with a few drops of sesame oil to prevent sticking.

Make the sauce: In a bowl, whisk hoisin, soy, oyster sauce, rice vinegar, brown sugar, broth, and cornstarch. Taste and adjust sweetness or saltiness. You want a balanced, slightly sweet-savory base.

Heat the pan: Use a large skillet or wok over high heat. Add 1 tablespoon oil and swirl until shimmering.

Sear the beef: Spread the beef in a single layer. Don’t crowd the pan. Sear 1–2 minutes per side until just browned. Remove to a plate. It will finish cooking in the sauce.

Stir-fry aromatics: Add another tablespoon of oil. Toss in garlic, ginger, and the white parts of the green onions. Stir 30 seconds until fragrant. Avoid burning the garlic.

Add vegetables: Stir-fry your chosen veggies 2–3 minutes. They should stay bright and crisp-tender. If using harder veg like broccoli or carrots, slice thin or steam briefly first.

Combine with sauce: Return beef to the pan. Whisk the sauce again and pour it in. Stir as it bubbles and thickens, 1–2 minutes.

Add noodles: Toss noodles into the pan, coating them in the glossy sauce. If it feels dry, splash in a little water or broth. Season with a pinch of salt or soy if needed.

Finish and serve: Stir in sesame oil and the green onion tops. Sprinkle sesame seeds and chili flakes if you like heat. Serve hot.