Katsu burgers

Instructions

1. If making the burger buns, melt the butter in a small saucepan over low heat. Add the milk and bring the mixture to body temperature (about 37°C/98°F). Remove from the heat, add the yeast and leave for 10 minutes, or until the mixture starts to foam.
2. Place the dry ingredients into the bowl of a stand mixer fitted with a dough hook. Add the milk mixture and 1 egg and knead for 8 minutes, until the dough is stretchy.
3. Transfer the dough to a clean, lightly oiled bowl, cover with plastic wrap and set aside to rest in a warm place for 45 minutes, or until doubled in size. Form the dough into 12 evenly sized rolls, cover again and set aside to rest for another 30 minutes.
4. Meanwhile, preheat the oven to 200°C (400°F) and line a baking tray with baking paper. In a small bowl, beat the remaining egg with 2 tablespoons of milk to make an egg wash.
5. Pour 250 ml (8½ fl oz/1 cup) water into a metal baking tin and place on the bottom of the oven. Place the rolls on the lined baking tray, leaving enough room for each one to expand. Brush the tops with egg wash and bake for 15 minutes, or until the rolls sound hollow when tapped. Transfer to a wire rack and allow to cool before using.
6. To make the burger sauce, combine the mirin and sake in a large saucepan and bring to the boil over medium-high heat. Boil until the aroma of alcohol has dissipated or the liquid is reduced by half, then add the remaining ingredients, along with 100 ml (3½ fl oz) water and cook, stirring, until the sugar and miso are dissolved. Remove from the heat and allow to cool before storing in an airtight container in the refrigerator, where it will keep for up to 1 month.
7. Combine the onion and cabbage with the salt and place in a colander for 10 minutes to draw out water. Squeeze out the excess liquid and transfer the vegetables to a large mixing bowl.
8. Mix in the minced beef, 2 tablespoons panko and 1 egg until well incorporated, then season with salt and pepper. Divide the mixture into 4 patties and place on a lined baking tray. Freeze the patties for 1–2 hours to set their shape and make it easier to crumb.
9. To create the crumbing mixture, whisk the milk and the remaining eggs in a bowl until homogenous. Place the flour on a large plate, season with salt and pepper and stir to combine. Place the remaining panko on a separate plate and line a third plate with baking paper.
10. Take a patty and coat it in the seasoned flour. Brush off any excess and dip the patty in the egg mixture, followed by the panko, making sure the patty is well coated in breadcrumbs. Transfer to the lined plate and repeat with the remaining patties, then place in the refrigerator until you are ready to fry.
11. Fill a large, heavy-based saucepan one-third of the way with oil. Heat over medium heat until small bubbles form on the surface of a wooden chopstick inserted into the oil – approximately 160°C (320°F). Deep-fry the patties for 5 minutes each and drain on a rack.
12. Split the burger buns in half and toast in a toaster or under the grill (broiler).
13. To assemble, lay the four bottom buns out onto a clean work surface. Place a patty on each of the bottom buns and top with the burger sauce, shredded cabbage and mayonnaise. Finish with the top bun and serve immediately.