In a medium bowl, combine thinly sliced flank steak with cornstarch, oil, water, and baking soda. Mix well and let marinate for at least 30 minutes.

Wash and chop the bok choy, mushrooms, and sugar snap peas. Set aside.

In a small bowl, mix warm water, sesame oil, light soy sauce, dark soy sauce, oyster sauce, and sugar. Stir well.

Heat a wok on high heat. Add neutral oil, then quickly add the marinated beef. Sear for about 30 seconds on each side.

Using the same wok, add remaining oil, ginger, and garlic. Stir until fragrant, about a few seconds.

Add mushrooms first, stir for 15 seconds, then add sugar snap peas and bok choy, cooking until the bok choy is bright green.

Return beef to the wok and pour in the prepared sauce, stirring until it simmers. Add cornstarch slurry and mix until sauce thickens.

Transfer to serving plates and serve hot over steamed rice or noodles.