Cut your beef into thin slices against the grain. Marinate this with soy sauce, Shaoxing wine, cornstarch, oil, baking soda, and white pepper. Mix gently to coat the beef. Let marinate for at least 15 minutes while you prepare the rest of the ingredients.
Prepare the sauce by combining all the ingredients together until smooth. You may also prepare the bell peppers, onions, garlic, and ginger at this stage.
Heat 2 tbsp of oil in a wok or large pan over medium-high heat. Briefly fry the marinated beef on all sides until browned all over (you may need to do this in batches to avoid overcrowding). Once seared, set the beef aside.
In the same pan, fry the onions and bell peppers for 2-3 minutes until lightly softened. Add in the garlic and ginger, and continue to stir-fry for 1-2 minutes until fragrant.
Pour in the prepared sauce. Let simmer and reduce for about 1 minute until thickened slightly. Add back in the beef and pour in the sesame oil. Stir-fry for an additional 1-2 minutes, or until the sauce coats and clings to the beef and vegetables.
Serve warm with rice and veggies. Enjoy!
