Marinade the beef: In a bowl, add and mix together the marinade (corn starch, baking soda, black/white pepper, sugar, sea salt, rice wine, soy sauce, sesame oil and avocado oil) with sliced beef for at least 30 minutes.
Mix sauce: In a bowl, add and mix together soy sauce, oyster sauce, sugar, sesame oil, corn starch, and water.
While the beef marinades, steam the string beans until slightly cooked. Do not cook the string beans all the way.
Heat the wok or large skillet on high heat and add oil. Add and stir-fry the garlic and ginger. Add the beef and stir-fry until beef is cooked. Add the string beans and sauce. Stir everything together until the sauce thickens. Serve immediately in a bowl over rice!