Cook the spaghettini in salted water until al dente.
Heat some olive oil in a large pan or wok. Peel the onion, cut in half and cut into rings. Then add the onion, garlic, sliced ginger, peanuts and chilli to the pan or wok and fry. Cut the beef into strips and add. Fry over high heat and then add soy sauce, peanut oil, bean sprouts and chopped coriander. If necessary, add salt, pepper and cayenne pepper to taste.