How to make : The Summer Sandwich with Tuna in a Can Rizzoli
Caramelize the onions: Slice the red onion into rounds. In a skillet, cook it with a drizzle of oil, brown sugar and balsamic vinegar for 15-20 minutes over low heat until soft and glossy.
Toast the bread: Cut the bread into slices and toast them in a frying pan (preferably a grill) or in the toaster oven until they are golden brown and crispy.
Assemble the sandwich: On one slice of toast, arrange the scamorze slices, caramelized onions, slices of Rizzoli tuna, fresh arugula and chopped walnuts to give crunch. Close with the second slice of bread and press lightly.
Optional: heat the sandwich. To slightly melt the scamorza cheese, you can repass the sandwich in a hot pan, pressing it lightly with a spatula or weight for 1-2 minutes per side.