Cut the avocado in half, remove the pit, and peel it.
Slice the avocado.
Spread a little butter or olive oil on the bread.
Toast the bread in a toaster or pan, then place it on a plate.
Put the avocado slices on top of the toasted bread.
Sprinkle with salt, pepper, and lemon juice.
Add tomatoes, onions, cheese, or other toppings as desired.