In a mixing bowl, combine the flank steak slices with baking soda, light soy sauce, peanut oil, and cornstarch. Allow to marinate for at least 15 minutes.

In a separate bowl, whisk together chicken broth, oyster sauce, light soy sauce, dark soy sauce, sugar, cornstarch, and sesame oil until smooth. Set aside.

Heat one tablespoon of peanut oil in a large skillet over medium-high heat. Add the marinated beef in a single layer. Cook for about 1 minute on each side until golden brown. Remove and set aside.

In the same skillet, add the remaining tablespoon of peanut oil, chopped onion, minced garlic, and ginger. Stir-fry for about 2 minutes until onions are translucent.

Add asparagus to the skillet and stir for about 1 minute until slightly tender while remaining crisp.

Pour the prepared sauce into the skillet, stir to combine, and allow to simmer for 1-2 minutes until thickened. Return the beef and toss to coat.

Transfer to a serving plate and serve hot over steamed white rice.