Fill a large saucepan with 2 to 3 inches of water and bring to a boil. Add the vinegar and a big pinch of salt. Adjust the heat so the water simmers. Working with one egg at a time, break into a cup and gently slip into the water, holding the cup close to or even just under the surface of the water. Quickly repeat with the remaining eggs. Cook until the whites are firm and yolks cooked as you like, about 3 minutes.