Heat oil in a small non-stick frying pan on medium heat and fry the 2 eggs together to make one circle until they are cooked on one side. Sprinkle a small amount of salt on the eggs and then flip the eggs over to cook the other side. The eggs are done when the yolks are cooked in the middle.
Flip half of the fried eggs over the other half like an omelet.
Spread 1 tablespoon of mayo on one side of each bread.
Place fried eggs on top of one slice of bread and sprinkle ground black pepper on the eggs.
Place onions on the eggs and top with the second slice of bread.