Set egg out to warm to room temperature for best results.
Fill a saucepan with at least 3 inches of water, then add vinegar.
Place saucepan over high heat until water is just beginning to boil, then reduce temperature to the point where the water is almost boiling, but not quite (a few bubbles are coming up the sides).
Break an egg into a small cup, bowl, or ladle.
Softly stir water with a large kitchen spoon to get it spinning in a whirlpool. Pour egg into the center.
Set timer and cook 3 minutes for a very soft yolk or 4 minutes for a slightly thicker yolk.
Remove immediately with a slotted spoon and allow the water to drain, or place on a paper towel, or in a small bowl that can be tipped to drain.