Heat butter or oil in a skilled over medium heat.
Crack egg into the pan and reduce heat to low. Cook until whites are opaque.
While the egg is frying, toast the bread until crisp and golden.
Spread mayonnaise or butter over the toast.
Layer cheese over the fried egg and allow it to melt.
Place the egg with melted cheese on top of the prepared toast.
Sprinkle with sea salt and enjoy warm.