Slice the red pepper.
Cut the broccoli into bite-sized florets.
In a mixing bowl, whisk together soy sauce, water, brown sugar, ground ginger, garlic powder, onion powder, salt, and black pepper. Set aside.
In another bowl, mix cornstarch with a little bit of water to create a slurry. Set aside.
Heat 2 tablespoons of vegetable oil in a large skillet or wok over medium-high heat.
Add the beef slices and cook until browned, about 3-4 minutes. Remove the beef from the skillet and set aside.
In the same skillet, add the remaining tablespoon of vegetable oil.
Add the sliced red pepper and broccoli florets to the skillet. Cook for about 3-4 minutes, or until the vegetables are tender-crisp.
Return the cooked beef to the skillet with the vegetables.
Pour the prepared sauce over the beef and vegetables in the skillet.
Stir the cornstarch slurry to recombine, then pour it into the skillet.
Cook, stirring constantly, until the sauce has thickened, about 1-2 minutes.
Once the sauce has thickened and everything is heated through, remove from heat.
Serve hot over rice or noodles.
