First, gently immerse each egg in the shell in boiling water for 8 seconds, adding no more than one layer of eggs to the pan and removing them in the same sequence in which they were added. The heat cooks the thin layer of white just inside the shell, separating it from the thick white around the yolk. Don't worry if the shells crack. You can poach the eggs at once, or chill them up to two days. Best of all, when you poach these eggs side by side, they don't stick together.
To poach fill pan with enough water to cover an egg out of the shell by at least 1 inch. A 12-inch frying pan holds as many as 10 large eggs. Set pan over high heat just until one or two bubbles break the surface of the water. Then reduce heat so bubbles that form on pan bottom only pop to the surface occasionally. An active boil toughens and breaks up the eggs.
Crack eggshells, one at a time, holding each shell close to the water surface as you break it open and letting the egg slide gently into the water (stretching also tears up an egg).
Cook until eggs are as done as you like, poking gentlly with a spoon tip to check firmness. Soft but safely heated yolks take 4 to 5 minutes. As the eggs are cooked, lift them from the water with a slotted spoon. Serve, or if making ahead, immerse in ice water, cover, and chill up to two days.
To reheat, immerse eggs in water that's just hot to touch (but not hot enough to cook them further) until they feel warm, 5 to 10 minutes. Lift out with a slotted spoon (or your hand), drain, and serve.