First things first, we need to ready that pepper! Take the 6 grams of whole black peppercorns and crush them coarsely. I prefer using a mortar and pestle for this task, as I love grinding spices to unleash their full flavor. If you don’t have one, simply throw the peppercorns into a freezer bag and use a rolling pin to smash them up. The goal is to release that pungent aroma without turning them into dust.

Grab a mixing bowl and whisk together the oyster sauce, Shaoxing wine, soy sauce, toasted sesame oil, and most of the crushed black pepper (save a little for later). Now, sprinkle in the potato starch and mix until it’s lump-free. This is where all the flavor magic happens! Add the beef tenderloin cubes to the bowl, making sure each piece is evenly coated. Let it marinate while you chop your vegetables.

Chop your onion and bell peppers into cubes. The size doesn’t have to be perfect, but I suggest aiming for ½-inch pieces. This way, they’ll cook evenly and retain a nice crunch. Also, don’t forget to chop your garlic; you want it ready to go!

Heat a frying pan over medium-high heat until it’s hot. Add the 1 tablespoon of vegetable oil. Using tongs, carefully add the marinated beef into the pan in a single layer. You want to leave as much of the marinade in the bowl as possible—don’t worry; it’ll come back into play soon. Let the beef fry undisturbed until it’s golden brown on one side, then flip to brown the other side.

Once the beef is nicely browned, toss in the chopped onion, bell pepper, and garlic. Turn the heat up to high and stir-fry everything together. Keep tossing the ingredients around in the pan to ensure even cooking and to prevent them from sticking. The onions should turn translucent, signaling that it’s time for the next step.

Pour any remaining marinade into the pan, giving everything a good toss until the beef is shiny and coated with the delicious sauce. Cook for an additional minute to let the flavors meld. Now, it’s time to serve! Dish it up alongside rice or noodles and garnish with the leftover black pepper and a sprinkle of chopped green onions, if you’re feeling fancy.