Make the sauce: In a small bowl, mix hoisin sauce, oyster sauce, soy sauce, brown sugar, black pepper, salt, baking soda, rice flour or cornstarch, rice vinegar, sesame oil, and water.
Marinate the Beef: Slice the beef knuckle steak to ⅓-inch thickness and marinate it in the sauce for 30 minutes.
Saute the Beef: Meanwhile, slice the onion and mince the garlic. Heat olive oil in a wok over medium-high heat. Sauté the onion and garlic for 3 minutes. Add the marinated steak and cook for 10 minutes on high heat, stirring occasionally, until the steak is dark brown.