1Combine beef mince, mushrooms, onions, peppers, garlic powder, ground ginger, chili powder, and olive oil on a baking tray.
2Cook in the oven at 200°C for 12–15 minutes, or in an air fryer at 200°C for 8–10 minutes.
3Prepare the sweet and smoky Korean marinade by mixing gochujang paste, sesame oil, rice wine vinegar, dark soy sauce, chilli flakes, brown sugar, and sesame seeds.
4Coat the beef and vegetables with the marinade.
5Return to the oven for 5–8 minutes until sticky and caramelized, or air fry for 3–5 minutes more until sticky and caramelized.
6While the beef is cooking, combine cucumber, red onion, spring onion, brown sugar, chili flakes, sesame oil, white wine vinegar, and soy sauce in a mixing bowl for the smashed cucumber salad.