Mix the soy sauce, sugar, 3 tablespoons rapeseed oil, ginger, and garlic in a bowl to make a marinade.
Cut the beef steak into strips and place in the marinade. Refrigerate while preparing other ingredients.
Bring 300 ml water with a pinch of salt to a boil in a pot. Add the basmati rice, reduce heat to low, cover, and cook for 15-18 minutes until the rice is tender and the water is absorbed.
Peel the onion and cut into strips. Cut the spring onions into rings.
Heat some of the remaining rapeseed oil in a pan over medium-high heat. Fry the onion strips for 4-5 minutes until softened, then set aside.
Heat the remaining oil in the same pan over medium-high heat. Remove the beef from the marinade and fry, stirring occasionally, for 3-4 minutes until cooked through.
Just before the beef is done, return the onion strips to the pan and add the spring onions. Toss together for 1 minute.
Sprinkle sesame seeds and a pinch of chili powder over the beef mixture.