Place a small pot of water with vinegar on the stove and bring to a boil then turn down to simmer.
Crack an egg into a small ramekin and slowly add to boiling water, 1 at a time. You can add both eggs to the one pot and do not swirl. The yolk will drop and the whites will follow. Cook for 3-4 min for a slightly runny egg, longer if you wish to have a harder yolk.
While eggs are cooking place bread in the toaster.
Cut the avocado in half and core the seed out. Set aside one half for another time.
Butter the toast lightly
Mash each half of the half of the avocado onto each slice of toast, lightly salt the avocado.
Place lettuce on top of the avocado.
Remove eggs with a slotted spoon, ensure all extra water has dripped off, and carefully place each egg in the middle of the lettuce, on each slice of toast.
Salt and Pepper the tops once again, to taste.