1 roll **(brioche, kaiser, or sourdough all work well)**
1 egg
3 pieces thin sliced mortadella
2 slices cheese **(cheddar or american)**
Dijon mustard
Mayonnaise **(ideally kewpie)**
steps
Place pan over medium-high heat and drape in mortadella slices as a mound in the pan
While the mortadella fries on one side, add some butter and griddle the roll on the other
Once the roll is done, remove and let cool
Flip the mortadella, rearranging into a bun-sized mound if necessary, and top with a slice of cheese
Spread equal parts mayo and mustard on bottom slice of toasted roll once cool
Once the cheese is melted, transfer the fried mortadella to the roll
Crack and fry egg until desired doneness, seasoning with salt and pepper
Flip egg, add slice of cheese on top, and cover to melt
Transfer egg on top of mortadella, top with other half of roll, and serve immediately
notes
The mortadella is easier to deal with than sausage or bacon, and has a better accompanying flavor than either in my opinion
The mixture of mayo and dijon mustard adds a nice tang to the sandwich, cutting through the richness of the rest of the sandwich
Frying the mortadella as a mound **(instead of as flat slices like you would bacon)** gives a nice textural contrast, with charred crispy bits at the edges, but a more hammy consistency in the center
I prefer an over-medium egg in this sandwich, which ensures it isn't too messy, but still has a nice jammy yolk component.