Combine the soy sauce, oyster sauce, hoisin sauce, Shaoxing rice wine or dry sherry, toasted sesame oil, and brown sugar in a small bowl. Stir in the cornstarch slurry made with 1/2 teaspoon cornstarch and 1 tablespoon cold water.

Cook the dried egg noodles according to the package directions. Drain, rinse briefly under cold water, and toss with a small amount of oil so the strands remain separate.

Pat the beef dry and slice it thinly across the grain. If desired, partially freeze the beef first because the firmer texture makes thin, even slices easier.

Heat a wok or large skillet over high heat. Add 1 tablespoon oil and stir-fry the beef in a single layer for 1-2 minutes, working in batches if needed, then remove it while slightly underdone.

Add the remaining oil to the pan. Stir-fry the onion, carrot, red bell pepper, and broccoli for 3-4 minutes, until the vegetables are crisp-tender.

Add the chopped garlic and freshly grated ginger. Cook for about 30 seconds, stirring constantly, until fragrant.

Return the beef to the pan and add the cooked noodles and sauce. Toss continuously for 2-3 minutes, adding 2-3 tablespoons water as needed, until the sauce thickens slightly and coats everything.

Finish with sliced spring onions and optional sesame seeds. Serve immediately while the noodles are hot and the vegetables still have a pleasant bite.