Begin by slicing the flank steak into thin strips about ⅛ to ¼ inch thick. Aim for even thickness so that your Pepper Steak with Tender Beef and Savory Pepper Sauce cooks evenly; set aside after slicing.

In a mixing bowl, combine the sliced beef with 1 ½ tablespoons of water, 2 teaspoons of cornstarch, 2 teaspoons of neutral oil, 2 teaspoons of oyster sauce, 2 teaspoons of Shaoxing wine, and ¼ teaspoon of baking soda. Mix gently and let it marinate for at least 30 minutes; for tougher cuts, consider marinating overnight to achieve maximum tenderness.

While the beef marinates, prepare the savory sauce. In a separate bowl, whisk together ½ cup of low sodium chicken stock, 1 tablespoon of cornstarch, 1 ½ tablespoons of oyster sauce, 1 tablespoon of Shaoxing wine, 1 tablespoon of light soy sauce, 1 teaspoon of dark soy sauce, ½ teaspoon of sugar, ½ teaspoon of sesame oil, and ⅛ teaspoon of white pepper. Set the sauce aside for later use.

Next, cut the green bell pepper, half of the red bell pepper, and the onion into 1-inch pieces or thin strips. Keep your vegetable cuts uniform to ensure even cooking, and set them aside until you're ready to stir-fry.

Heat a wok or large skillet over high heat until it starts to smoke. Add 1 tablespoon of neutral oil and quickly sear the beef strips for about 30 seconds per side, until they’re 80% cooked. Remove the beef from the pan and return it to the marinating bowl with its juices.

Reduce the heat to medium-high and add the remaining 1 tablespoon of neutral oil to the hot wok. Sauté ½ teaspoon of minced ginger for a few seconds, then add 2 chopped garlic cloves, the bell peppers, and onion. Stir-fry this vibrant mix for 1 minute until they just begin to soften and release their enticing aroma.

Take the beef out of the bowl and add it back into the wok with the sautéed vegetables. Stir for about 15 seconds to combine the ingredients thoroughly. Then, increase the heat to high again, and pour the prepared sauce over the beef and vegetables. Stir continuously until the sauce thickens, about 1-2 minutes; adjust with more stock or water if necessary.

Once the sauce has reached the desired thickness, remove the Pepper Steak with Tender Beef and Savory Pepper Sauce from the heat. Serve it hot over a bed of steamed rice to soak up all that delicious sauce. Enjoy every bite of this quick and satisfying homemade dish!