In a medium bowl, combine the sliced beef flank steak with baking soda, light soy sauce, peanut oil, and 1 teaspoon cornstarch. Toss well and marinate for about 15 minutes.

In a separate bowl, whisk together the chicken broth, oyster sauce, dark soy sauce, sugar, and the remaining cornstarch. Set aside once mixed.

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

In the same skillet, add another tablespoon of peanut oil followed by the sliced onion, garlic, and ginger. Stir-fry for about 2 minutes until fragrant.

Incorporate the chopped asparagus into the skillet, cooking for about 1 minute until bright green and slightly tender.

Stir the prepared sauce into the skillet with beef and vegetables. Cook until the sauce thickens, about 1-2 minutes.

Return the seared beef to the skillet, gently mixing everything to coat. Cook for an additional minute until heated through. Serve hot.