Gather all your ingredients and utensils.
Heat a non-stick skillet over medium heat.
Add butter or oil to the skillet.
Crack the egg into the skillet and cook to your desired doneness.
Season the egg with salt and pepper.
While the egg is cooking, toast the bread slices until golden brown.
Once the egg is cooked, place it on one slice of toasted bread.
Add the lettuce on top of the egg.
Optional: add cheese, tomato, or avocado.
Top with the second slice of bread, slice in half, and serve.