
Prepare the eggs (preferably white) by covering in cold water, with at least an inch between the eggs and the top of the water. Bring the water to a boil, then turn off heat and cover. Let eggs steep for ten minutes, then cool eggs. (In the photo above, white eggs are opposite their brown counterparts).
Prepare a dye by bringing 4 1/2 cups of water to a boil. Add 2 tablespoons of vinegar plus the dyeing ingredient (below). Cover, and bring again to a boil. Simmer at a medium-low flame for 30 minutes. Cool ideally to room temperature (warm is okay, but may cook eggs), and transfer to a glass jar or small pot.
While the dye cools, you can make designs on the eggs. Use a paintbrush to apply a layer of egg white onto the egg. Gently press on your leaf of choice (e.g., parsley, carrot leaves, fennel leaves; the photo shows the last two), then place the egg in the middle of a 4" square of nylon stocking. Stretch the nylon taut, and secure with some string. Rinse off the extra egg white by swishing in cool water.
When dye is cool, submerge boiled eggs in one layer (e.g., up to 6 large). Let sit overnight in the refrigerator: the longer the eggs sit, the deeper the color. This year's batch of eggs were in the dye for at least 20 hours; a 9-hour overnight wasn't enough.
Transfer eggs to a rack to dry, removing nylon and leaf if necessary. Refrigerate the dried eggs until use. Before displaying the eggs, apply a light coat of olive oil with a paper towel.
Blue: 4 cups chopped red cabbage. Boiling the eggs in the dye doesn't affect the eggs at all.
Next year, I may try for the whole rainbow: orange (red onion skins; I'll try soaking in cold dye unlike last time); yellow (annatto seeds); green (liquid chlorphyll); purple (freeze dried blueberries). Ratio: a cup of dye ingredient per 5 cups of water.