In a mixing bowl, combine soy sauce, oyster sauce, and cornstarch to create a flavorful marinade. Add your thinly sliced beef, ensuring every piece is coated well. Let it soak for at least 15 minutes.

Heat vegetable oil in a large skillet over high heat. Once shimmering, add the marinated beef, searing for 1-2 minutes on each side until browned. Remove and set aside.

In the same skillet, add the remaining oil and sauté the sliced bell peppers and onions over medium-high heat for 3-4 minutes until tender but still crisp.

Add minced garlic and freshly grated ginger to the skillet, stirring constantly for another minute to infuse flavors.

Return the seared beef to the skillet, pour in beef broth, and cook for an additional 2-3 minutes to thicken the sauce.

Season with salt and pepper to taste and serve hot over rice or noodles.