1. Slice the sirloin steak thinly against the grain.
2. Peel and slice the onions into thick slices.
3. Deseed and slice the green and red bell peppers.
4. Mince the garlic and ginger.

1. Toss the steak slices with salt and 1 tsp of black pepper.
2. Heat 3 tbsp of sunflower oil and sesame oil in a wok over high heat.
3. Add the steak and stir-fry for 2-3 mins until browned.
4. Remove the steak and set aside.
5. Add the remaining sunflower oil to the wok, then stir-fry the onions and bell peppers for 3-4 mins until they start to soften.
6. Mix cornflour, soy sauce, oyster sauce, and rice wine in a bowl.
7. Add beef stock and remaining black pepper, stirring to combine.
8. Add garlic and ginger to the wok, cooking for 1 min.
9. Pour in the sauce, bring to a simmer, then return the steak to the wok, stirring to coat.
10. Cook for an additional 2 mins.

Serve the black pepper beef over cooked rice, ensuring each portion has a generous amount of sauce and vegetables.