These reddish-brown eggs dyed with onion skins seem appropriately colored for Good Friday. Simply boil the eggs with lots of skins from ordinary yellow onions. We cook the eggs at low heat for at least an hour. The longer the boiling time, the richer and deeper the color. The low heat helps to seal the yolk in a neat pocket. If no cracks develop, the eggs may be kept for several years. To create a print of leaves or flowers, using cheesecloth, wrap the plant tightly against the egg. Tie the top and bottom ends with cooking twine and add the egg to the pot.