Lightly butter one side of each slice of bread.
Smash the avocado and add a pinch of salt. Mix to combine and set aside.
Place one slice of bread buttered side down in a frying pan over medium. Top with fried egg, cooked bacon, and sliced tomato.
On the remaining slice of buttered bread, spoon a generous amount of smashed avocado on the unbuttered side and place the avocado side down on top of the tomato.
Cook in the frying pan for a minute or two and gently flip the sandwich to brown the other side.
Remove from pan, slice in half, and serve with your favorite sandwich accompaniments.