h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Boil a dozen eggs, shell half and pickle refrigerated overnight in vinegar. Crack the other half under water to facilitate peeling and store refrigerated under water. Bring sufficient chopped red cabbage (takes one average sized red cabbage per half dozen eggs) to bed and cover the eggs to a boil in an absolute minimum of water, steam on low heat covered until tender, chill. The morning after, lay out a bed of steamed red cabbage in the bottom of a serving dish, lay out the shelled eggs on top of it and cover with the remainder of the red cabbage.

The pickled eggs will turn pink, and the unpickled eggs blue (litmus effect), with mottling wherever they're in contact with cabbage or other eggs. Other colors are possible (with a rhubarb pre-pickle for example).