Ingredients:

For the Steak:

1 lb flank steak or sirloin, thinly sliced against the grain
2 tbsp soy sauce
1 tbsp cornstarch
1 tbsp vegetable oil

For the Stir-Fry:

2 large bell peppers (red, green, or yellow), sliced into thin strips
1 large onion, sliced into thin wedges
3 cloves garlic, minced
1 tbsp fresh ginger, minced
2-3 tbsp vegetable oil, divided
For the Sauce:

1/4 cup soy sauce
1/4 cup beef broth or water
1 tbsp oyster sauce
1 tbsp hoisin sauce
1 tbsp rice vinegar
1 tsp sugar
1 tsp cornstarch
1/2 tsp black pepper
1/4 tsp red pepper flakes (optional, for spice)
For Garnish:

Sliced green onions
Sesame seeds
Instructions:
Marinate the Steak:

Prepare the Beef:
In a bowl, combine the thinly sliced steak with soy sauce and cornstarch. Toss to coat evenly.
Let the beef marinate for at least 15 minutes to tenderize.
Prepare the Sauce:

Mix the Sauce:
In a small bowl, whisk together soy sauce, beef broth (or water), oyster sauce, hoisin sauce, rice vinegar, sugar, cornstarch, black pepper, and red pepper flakes (if using). Set aside.
Cook the Steak:

Sear the Steak:
Heat 1 tablespoon of vegetable oil in a large skillet or wok over high heat.
Add the marinated steak slices in a single layer and cook for 1-2 minutes per side until browned but not fully cooked through.
Remove the steak from the skillet and set aside.
Stir-Fry the Vegetables:

Cook the Vegetables:
In the same skillet, add another tablespoon of oil if needed.
Add the sliced bell peppers and onions. Stir-fry for 3-4 minutes until they are tender-crisp.
Add the minced garlic and ginger, and stir-fry for another 1-2 minutes until fragrant.
Combine and Cook:

Return the Steak:

Return the seared steak to the skillet with the vegetables.
Pour the sauce over the steak and vegetables.
Simmer:

Stir everything together and simmer for 2-3 minutes, until the sauce thickens and coats the beef and vegetables.
Serve:

Garnish and Serve:
Serve the Chinese Pepper Steak hot, garnished with sliced green onions and sesame seeds.
Enjoy your flavorful and spicy Chinese Pepper Steak with Onions!