Tea Eggs (Chinese Marbled Eggs)

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.

http://ostermayer.tumblr.com/post/190848933/tea-egg-ingredients-6-eggs-3-tablespoons-soy (and photo credit), via Sharp as Teeth and Stars.