Break up the beef with a fork and place it in a bowl with 1 tablespoon of the soy sauce, 2 teaspoons of the sesame oil and the rice wine. Stir in the sugar and salt and season with a generous grinding of black pepper. Leave to marinate for 15 minutes.
Heat 2 tablespoons groundnut oil in a wok over a high heat until the oil starts to shimmer. Add the onion and chilli and stir-fry for 2 minutes, until it begins to colour. Add the beef and let the meat cook until it becomes golden but not browned. Drain in a sieve.
Wipe the wok clean, return it to the heat and pour in the remaining groundnut oil. While it heats up again, combine the eggs, remaining soy sauce and sesame oil and season lightly with freshly ground black pepper. Tip the mixture into the hot oil and scramble for about 1 minute until mostly set, but still moist and creamy. Return the cooked beef to the wok and stir-fry for 1 minute. Scatter with coriander and serve with rice, if liked.