Step 1

Whisk cornflour and soy sauce in a jug until smooth. Stir in black bean sauce, chilli sauce and stock.

Step 2

Heat a wok over medium-high heat. Add 1 tbs peanut oil. Swirl to coat. Cook beef, in batches, for 1 to 2 minutes or until browned. Transfer to a bowl.

Step 3

Heat remaining 1/2 tbs peanut oil in wok. Add brown onion. Stir-fry for 2 minutes or until softened. Add capsicum, garlic and ginger. Stir-fry for 3 to 4 minutes or until capsicum is just tender. Add mushroom. Stir-fry for 2 minutes or until softened.

Step 4

Return beef and juices to wok. Add sauce mixture. Stir-fry for 2 to 3 minutes or until sauce boils and thickens. Add green onion. Toss to combine. Serve.