First of all, that question is one of the greatest conversation starters of all time. Seriously. Try it. No one gives the same answer. It's amazing.
Karen and I have been collecting fried egg sandwich ideas from everyone we talk to. The variety is staggering.
To start with there's the wide spectrum of yolk hardness from over easy to fried hard to broken.
Here are the bread choices we have collected:
white toast, wheat toast, ciabatta, English muffin, Italian bread, bagel, croissant, biscuit, brioche, rye, cracked wheat
And the cheese:
provolone, cheddar, gruyere, gorgonzola, brie, swiss, American
And the meat:
bacon, Canadian bacon
arugula, tomato, bell peppers, onions, mushrooms, caramelized onions, parsley, fresh herbs
ketchup, mustard, mayonnaise, butter, harissa, tabasco sauce, horseradish, truffle oil, Hollandaise, Bearnaise
Holy Sandwich Batman! How will we choose?