Prepare the Beef: Place your thinly sliced beef in a medium bowl. Sprinkle over the 1 tablespoon of cornflour and toss well to coat each piece evenly. This technique, known as velveting, helps create a protective barrier that keeps the beef incredibly tender. Set aside.

Mix the Sauce: In a separate small bowl or jug, whisk together all the sauce ingredients EXCEPT for the cornflour slurry: soy sauce, water, honey, rice vinegar, sesame oil, minced garlic, and grated ginger. Set this aside near your hob.

Sear the Beef: Heat 1 tablespoon of oil in a large wok or frying pan over a high heat until it's shimmering. Add half the beef in a single layer, being careful not to overcrowd the pan. Cook for 1-2 minutes per side until deeply browned but not cooked through. Remove with a slotted spoon and set aside on a plate. Repeat with the remaining beef.

Cook the Vegetables: Add the remaining tablespoon of oil to the same wok. Add the broccoli florets and carrot slices. Stir-fry for 3-4 minutes until they begin to soften but are still vibrant.

Add Softer Vegetables: Add the sliced red pepper and the white parts of the spring onions to the wok. Continue to stir-fry for another 2-3 minutes until the pepper is crisp-tender. You want the vegetables to retain a bit of a bite. What works best for me is keeping everything moving constantly in the pan.

Combine and Add Sauce: Return the seared beef to the wok with the vegetables. Give your prepared teriyaki sauce a quick stir, then pour it all over the beef and vegetables. Bring the mixture to a lively simmer.

Thicken the Sauce: While the sauce is simmering, give your cornflour slurry a quick re-whisk and pour it into the wok. Stir continuously for 1-2 minutes. The sauce will thicken almost immediately, becoming glossy and coating everything beautifully.

Serve Immediately: Turn off the heat. Stir in the green parts of the spring onions. Serve your beef teriyaki stir fry straight away over fluffy steamed rice or noodles, garnished with a sprinkle of sesame seeds.