Off-Center Yolks and Flat-Bottomed Whites

Well-centered yolks for attractive slices or stuffed halves are easiest to obtain from fresh, high-grade eggs with small air cells and plenty of thick albumen. As eggs age, the albumen loses water and becomes more dense, which makes the yolk rise. Industry studies have found that you can increase the proportion of centered yolks somewhat by storing eggs on their sides instead of their ends. Various cooking strategies have also been suggested, including rotating the eggs around their long axis during the first several minutes in the pot, and standing them on end. None of these is completely reliable.