Make the sauce – In a jug or small bowl, combine the sauce ingredients, set aside.
Cook the beef – Heat the oil in a large heavy-based pan over high heat. Add the beef, break it up (so it covers more of the surface area of the pan), and allow it to cook, untouched, for at least 5–6 minutes – this will allow the beef to brown and develop crispy edges. Flip it, further breaking it apart with your spatula, and cook for a further 1–2 minutes or until cooked through.
Add the garlic and ginger – Stir the garlic and ginger in, cooking for 30 seconds.
Add the sauce – Pour the sauce over the beef and simmer for 1–2 minutes to coat the beef.
Thicken the sauce – Stir in the cornflour and water mixture. Cook for 30–60 seconds until the sauce thickens and clings to the beef.
Serve – Spoon over rice and top with cucumber ribbons, spring onion, sesame seeds and a drizzle of sesame oil.
