• Finely chop mortadella in a blender.
• Combine mortadella, ground meat, ricotta cheese, salt, grated lemon zest, and nutmeg in a bowl.
• Mix the mixture with your hands and divide it into 4 equal parts (forming balls) to make hamburgers of about 100g each, or make two for big eaters.
• Shape the balls into hamburgers using your hands (press the dough with the palm of your hand and even out the edges). Set aside.
• Arrange the onion slices in a pan with one part of the aromatics and a drizzle of oil, keeping the others aside. Cook until the slices are soft and lightly toasted (add a tablespoon of sugar for a caramelized effect, if you like).
• Cut a tomato into slices, making at least 4, arrange on a plate, and season with salt and olive oil.
• Cut the bread in half for stuffing and set aside.
• In the pan where you cooked the onion, arrange the aromatics on the bottom and the burgers on top, then cook over high heat for about 3-4 minutes per side, fading with lemon juice (use olive oil if you prefer).
• Meanwhile, heat the buns on both sides of the griddle.

Mortadella burger assembly

• On the first slice of bread, put 2 teaspoons of sauce (mayonnaise and ketchup), then a slice of onion, a slice of cheese, the bologna burger, more sauce, a slice of tomato, a slice of cheese, sauce again, and close the sandwich with the last layer of bread.

Tip

• When you prepare the ingredients, preheat the oven to 200C (392F) degrees so you can keep the buns warm while the cheese gets creamy.