In a large non-stick skillet, heat oil on medium heat. Cook onions until translucent, about 5-7 minutes, move to the side to make room for the others.
Next add salami to the same skillet, flip after about a minute on each side.
Crack your egg, smash yolk move around a lil bit and flip.
Place one slice of bread on the same skillet (if not enough room just use another heated skillet), top with Monterey Jack slices then spread Kewpie. Next, layer salami, egg and colby cheese. Top with second slice of bread, flip and cook until bottom side gets a little golden and cheese gets melty.