Velvet the steak: In a medium bowl, toss the sliced steak with 1 tablespoon cornstarch, the water, and the baking soda. Let it sit for at least 15 minutes, or up to 30, while you prep the vegetables.

Make the sauce: In a small bowl, whisk together the soy sauce, oyster sauce, brown sugar, beef broth, and the remaining 1 tablespoon cornstarch. Set aside.

Cook the peppers and onion: Heat 1 tablespoon of the vegetable oil in a large skillet or wok over high heat. Add the bell peppers and onion and stir-fry for 3-4 minutes until crisp-tender. Remove to a plate.

Sear the steak: Add the remaining 1 tablespoon oil to the same pan. Add the steak in a single layer and let it sear undisturbed for 1 minute, then stir-fry for another 1-2 minutes until mostly browned.

Add aromatics: Stir in the garlic and ginger and cook for 30 seconds until fragrant.

Add the sauce: Give the sauce a quick stir, the cornstarch settles, then pour it into the pan. Cook, stirring, for 1-2 minutes until it thickens and turns glossy.

Combine: Return the peppers and onion to the pan and toss to coat, cooking for another minute until the steak is warmed through and reaches at least 130-135°F for a tender, medium bite (145°F if you prefer it cooked through).

Serve: Serve hot over rice.