Preheat the oven to 180°C.
Peel the onions and carrots.
Cut the yellow onion into brunoise and cut the red ones into small wedges.
In a frying pan, sauté the yellow onion brunoise with a drizzle of olive oil for 5 minutes over low heat. Set aside.
Cut the carrots into julienne strips and mix with the red onion wedges. Place in a roasting tin. Season with salt and pepper and drizzle with olive oil. Place in the oven for 5 minutes then set aside.
At the same time, in a bowl, mix the ground beef with the egg, Worcestershire sauce, panko and yellow onions. Season with salt and pepper and divide the meat into 4 portions. Form into meat patties.
Pour a little oil into a frying pan and sear for 2 minutes on each side (depending on your desire). Transfer the meat patties to the roasting tin over the julienned carrots and onions.
Place 3 slices of IQF mozzarella on top of each patty, then grill for 3 to 4 minutes to melt the mozzarella.
Serve immediately!
For a more indulgent hambagu, insert Maestrella shredded mozzarella into each meat patty before cooking. You will have to cook them through so that the mozzarella is melted. You'll have a runny mozzarella meat heart!
For variety, you can make your meat patties by incorporating ground pork or ground veal. You just need to do 50/50 with the beef.