If your eggs bring to mind the Dr. Suess story, fear not. For one thing, "green" eggs are not in anyway unsafe, nor do they taste off—but they are unsightly. The discoloration around the yolk is due to a reaction between sulfur in the egg white and iron in the yolk. It occurs when eggs have been cooked for too long or at too high a temperature. Our method - cooking eggs in hot, not boiling, water, then cooling immediately - minimizes this.