Place the steak in the freezer for 30 minutes to firm up (this will make it easier to slice thinly).

After 30 minutes, remove from the freezer and carefully slice into thin (2mm) strips. Place the steak slices in bowl and add the soy sauce, gochujang, ginger, sugar, rice wine, minced garlic, black pepper, grated apple and sesame oil. Mix together, cover and allow to marinate for 30 minutes (place in the fridge if marinating for longer than that).

Once the steak has finished marinating, heat the oil on a high heat in a large frying pan. Add the steak, and fry for 4-5 minutes, turning occasionally until cooked and just starting to caramelise (if you find that a lot of liquid is released during frying, carefully drain it off and continue to fry the steak).

Remove the steak from the pan and place on a plate to rest for 2-3 minutes.

Add the sliced peppers to the pan and cook for 2-3 minutes until slightly softened. Remove from the pan.

Take the four slices of bread and brush the melted butter onto one side of each piece.

Place two of the pieces of bread, butter-side-down onto a chopping board or plate. Top with the cooked peppers, steak slices, sesame seeds and grated cheese. Sprinkle on the red onion, jalapenos and spring onions, then top with the other two bread slices. Make sure the butter-side is facing out.

Place both of the sandwiches in a frying pan over a low to medium heat and cook for 2-3 minutes each side until the bread is golden brown and the cheese has melted (you can do this part with a sandwich press if you have one).

Mix together the mayonnaise and minced garlic. Open the tops of the toasted sandwiches and drizzle on the garlic mayo and the sweet chilli sauce. Replace the tops of the toasted sandwiches, and serve immediately.