Fill pan with water to 5 cm (2 in) level and bring to a rolling boil (in which medium-sized bubbles appear on surface of water, but there is no turbulence below). Add vinegar, which will help the white coagulate. Crack open an egg and drop it quickly but carefully into the water. Repeat with remaining eggs. (If your egg white disappears into strands, the water is boiling too hard.) Bring the water back to the boil, then reduce immediately to a gentle simmer and cover pan with lid. Check after 3 minutes, and remove with a slotted spoon when whites have set. Drain on several folds of kitchen paper. Trim any messy edges with scissors and serve immediately.