Pour a little olive oil in a medium saucepan and add the chopped yellow onion and the garlic. Place this over medium heat.

Cook the garlic and onion gently for 2 minutes. Deseed the tomatoes and dice the tomato meat finely. Add it to the saucepan. Season with a little pepper and salt.

Stir well and reduce the heat. Put a lid on the pan and let the tomato simmer and fall apart for about 5 minutes. The sauce should be a little chunky. Stir well and add the tomato paste, half of the dried thyme and the red wine vinegar.

Stir and simmer for 3 more minutes. Check the seasoning and add extra pepper, salt, tomato paste or red wine vinegar to taste if necessary. Stir in the unsalted butter and some freshly chopped basil. Then take the tomato sauce off the heat and let it cool.

Add the veal mince to a large mixing bowl together with the egg yolk, the rest of the dried herbs and a little pinch of freshly ground black pepper and salt.

Knead the mince for a minute until it is nicely combined. Then divide the mince into 2 equal portions and make patties that are about an inch (2,5 cm) thick. Wrap them in some cling film.

Place the patties in the fridge and let them cool for 15 minutes. Remove the pork patties from the fridge and let them rest at room temperature for another 15 minutes. Then some olive oil in a medium non-stick pan and place it over medium-high heat. Once the oil is hot, add the veal patties.

Quickly sear them on one side for 2 minutes. Then flip them over and cook them until golden on the other side as well.

Then take the pan off the heat and let the burgers rest in the hot pan for 6 to 8 minutes. Flip them over regularly. Then inside should be warmed through but not cooked through. Keep the burgers rosé, pink on the inside! Transfer the cooked burgers onto plates and top with the tomato sauce and a slice of mozzarella. Grill the burgers for another couple of minutes until the cheese is nicely melted. Serve hot.