Put vinegar into boiling water. Turn down the heat. Add the eggs one at a time in separate sides of the pan. Cook for about 3-4 minutes (egg yolks should be partially runny while the egg white should be totally cooked).
Using a large slotted spoon: carefully scoop out the eggs, one at a time, drain, place on top of the buttered toast. Sprinkle with salt and pepper to taste.