Prepare the flank steak by slicing it against the grain.
Create the marinade by mixing soy sauce, rice vinegar, baking soda, and ginger.
Combine the flank steak with the marinade and let it sit for at least 30 minutes.
Coat the marinated beef with cornstarch.
Heat oil in a wok or large skillet over high heat.
Add the coated beef to the hot oil and stir-fry for 2-3 minutes until browned.
Add minced garlic and cook for another minute until fragrant.
Remove the beef from the pan and set aside while you prepare vegetables or sauce if desired.
