1Slice two brown onions and caramelize them in a hot pan with 50g butter and 1 tablespoon of brown sugar.
2Combine one shallot, a handful of fresh basil, a handful of fresh parsley, 1/4 cup olive oil, two red chillies, juice of 1/2 a lemon, and 1 teaspoon of garlic powder in a food processor/blender and pulse until combined.
3Slice ciabatta rolls in half, add slices of Jarlsberg cheese, and toast in the oven until the cheese is melted.
4Season the scotch fillet steaks with salt and pepper and sear in a hot buttered pan.
5Prepare the sandwich sauce by mixing 1 tablespoon whole grain mustard, 2 tablespoons kewpie mayonnaise, and 1/2 teaspoon sriracha in a small bowl.
6Slice the cooked steaks.
7Assemble the sandwiches by spreading the sandwich sauce on the toasted rolls, adding sliced steak, caramelized onions, fresh arugula, and drizzling with the chimichurri sauce.