Grana Padano Burgers with Coppa, Rocket & Red Onion

1. Preheat your oven to 200°C/Gas 6/Rack position middle shelf.
2. Start with the red onions. Get a medium sized (20cm) frying pan. Add the olive oil, the red onions, balsamic vinegar, soy sauce and 3 tbsp water. Cover. Sweat over a medium heat, stirring occasionally for 6-8 minutes or until the onions are soft. Take the lid off. Turn the heat to high. Fry the onions for 1 minute until lightly browned. Set aside.
3. Brush the brioche buns with the beaten egg yolk. Sprinkle 2 tablespoons of blended Grana Padano over the top of each. Pat the cheese on so that it sticks. Bake for 2-3 minutes until the cheese is just set on top.
4. Put a rack on a plate to rest the burgers on and a bowl to drain the fat into next to your cooker. Get a frying pan that is big enough for the burgers to fit in comfortably. Put the pan on a high heat. Add the oil then get the pan extremely hot. Put the burgers in the pan. If they don't make a loud sizzle, they won't brown, so, take them out again and wait. Fry for 2 minutes each side, over a medium to high heat, for medium rare to medium. ITurn the heat to medium and add 1 minute each side for medium and 90 seconds each side for medium well).
5. Put the burgers onto the rack. Drain the fat into the bowl. Put the burgers back into the pan. Put the pan on a low heat. Add half the butter. Fry for 30 seconds each side. Put the burgers back onto the rack to rest for at least 4 minutes.
6. Add 3 tbsp water to the pan. Bring to the boil. Stir vigorously. Take the pan off the heat. vStir in the remaining butter. This is not meant to be lots of sauce but a few spoonfuls of concentrated fried beef gravy. Season to taste. Put the burgers and the resting juices that will have dripped onto the plates into the pan. Turn the burgers in the juices until they are glossy and coated in their pan juices.
7. Spready the Grana Padano mayo all over the bottom buns. Follow with the onions, both tomatoes, rocket, burger patties, cooking juices, Coppa, Grana Padano shavings and rocket. Carefully put the tops on and secure with skewers. Any bits and pieces you have leftover, serve on the side.