Prepare the beef: In a medium bowl, toss the sliced beef with the cornflour, 1 tablespoon of vegetable oil, and a pinch of salt. Let it sit for 5 minutes while you prep the vegetables. The cornflour will feel slightly powdery at first, but as it sits, it will begin to adhere to the meat, creating a light coating that helps the sauce cling later.

Make the sauce: In a small bowl or jug, whisk together the beef stock, soy sauce, oyster sauce, sesame oil, brown sugar, and freshly ground black pepper. Stir until the sugar has dissolved completely—you should see a glossy, dark brown liquid with a rich, savoury aroma.

Sear the beef: Heat a large wok or heavy-bottomed skillet over high heat until it's smoking hot. Add 1 tablespoon of vegetable oil and swirl to coat. Add half the beef in a single layer—do not overcrowd the pan. Sear for 1–2 minutes without moving it; you'll hear a satisfying sizzle and see the edges turning a deep brown. Flip and cook for another 30 seconds. The beef should be browned on the outside but still slightly pink in the centre. Transfer to a plate and repeat with the remaining oil and beef.

Cook the aromatics and vegetables: Reduce the heat to medium-high. Add the remaining 1 tablespoon of oil, then the sliced onion. Stir-fry for 2 minutes until the onion softens and becomes translucent, with a slightly sweet smell. Add the red and green bell peppers and cook for 3–4 minutes, stirring frequently. The peppers will brighten in colour and begin to soften, but they should still have a slight crunch when you bite into them. Add the minced garlic and grated ginger, stirring constantly for 30 seconds until fragrant—the smell will be sharp and aromatic.

Combine everything: Return the seared beef and any accumulated juices to the wok. Pour the sauce over the top. Stir everything together and let it simmer for 1–2 minutes. The sauce will thicken slightly as it cooks, coating the beef and vegetables in a glossy, rich glaze. You'll see it bubbling gently around the edges.

Serve immediately: Spoon a generous portion of steamed rice into each bowl. Top with the pepper steak stir-fry and garnish with sliced spring onions. The contrast between the fluffy, white rice and the dark, glossy stir-fry is visually striking, and the steam rising from the bowl promises a deeply satisfying meal.