Season the beef with black pepper and chicken powder.
Toss the beef in cornstarch.
Deep fry the beef until crispy, then remove and set aside.
Make the sauce by combining soy sauce, rice vinegar, sugar, hoisin sauce, sesame oil, cornstarch slurry, ginger, garlic, and red pepper flakes.
Stir fry the vegetables in a pan.
Add the sauce and a portion of the crispy beef to the pan, tossing to coat.
Serve the dish garnished with green onions and sesame seeds.
