In a bowl, mix soy sauce, oyster sauce, cornstarch, and sugar to create a marinade.
Add the sliced steak to the marinade and let it sit for 20 minutes.
Heat 1 tbsp vegetable oil in a skillet over medium-high heat and cook the marinated steak until browned. Remove from skillet.
In the same skillet, add another tablespoon of oil and sauté garlic, ginger, onion, and bell pepper until tender.
Return the steak to the skillet, pour in beef broth, and stir until the sauce thickens.
Serve hot with steamed rice.