These visually striking eggs are produced by hard-boiling an egg, cracking the shell, and then steeping the egg in a flavored tea or broth. The batik-like marbling effect is more prominent when teas with high levels of tannin are used; the duration of the second boiling will influence both the color of the marbling and the degree to which the tea or broth flavor penetrates the egg.
Link (and photo credit), via Sharp as Teeth and Stars.
