Slice the Beef:

1. Cut the flank steak into thin strips against the grain, which helps keep the meat tender. Pat the slices dry to encourage good browning.

Stir-Fry the Vegetables:

1. Warm a small amount of neutral oil (such as canola) in a wok or large skillet over high heat. Add sliced bell peppers (red and green) and onion (if desired). Stir-fry for about 2–3 minutes, just until the peppers begin to soften but are still crisp. Set them aside on a plate.

Cook the Steak:

1. In the same pan, add a little more oil if needed. Place the sliced steak in the pan, leaving space between pieces so they sear rather than steam. Season lightly with salt and black pepper. Cook for about 1 minute on each side or until you see a brown exterior on the strips. Stir in garlic (and ginger if you’d like) for about 30 seconds, keeping an eye on the heat so they do not burn.

Combine with Sauce:

1. Return the bell peppers and onions to the pan with the steak. In a small bowl, whisk together soy sauce, beef broth or water, and a small amount of sugar or honey. Pour this mixture into the pan and let it come to a slight simmer. To thicken the sauce, stir in a cornstarch slurry (cornstarch mixed with a bit of cold water). Stir gently until the sauce reaches your preferred consistency.

Taste and Adjust:

1. Sample the sauce, and adjust any seasonings. Add chili flakes for heat if you like. Serve the finished Pepper Steak hot, ideally with rice, noodles, or whichever side you prefer.