In a mixing bowl, combine 360g thin-cut sirloin steak with 1 small egg, 4 tablespoons of cornflour, ¼ teaspoon salt, ¼ teaspoon black pepper, and ⅛ teaspoon white pepper. Mix well until the beef strips are entirely covered and allow them to sit for about 10 minutes.

Heat 3 tablespoons of sunflower oil in a non-stick frying pan over high heat until it shimmers. Carefully add the beef in batches and fry for about 5 to 6 minutes until the beef turns dark brown and crispy.

In the same pan, add the remaining 1 ½ tablespoons of sunflower oil and lower the heat to medium. Add 1 thinly sliced medium onion and sauté for 2 minutes. Introduce 1 deseeded red chili, 1 teaspoon minced ginger, and 3 minced garlic cloves. Stir and cook for another 30 seconds.

Pour in 2 tablespoons of rice vinegar, 3 tablespoons of dark soy sauce, 2 tablespoons of tomato puree, 6 tablespoons of caster sugar, 2 tablespoons of tomato ketchup, and 2 tablespoons of sweet chili sauce into the sautéed mixture. Stir well and let simmer for 2 to 3 minutes.

Return the crispy beef to the pan and toss everything together. Heat for an additional 1 to 2 minutes.

Transfer your finished Crispy Chilli Beef to a serving dish and serve with hot steamed jasmine rice or stir-fried noodles.