I found this recipe years ago on a blog written by fellow Orthodox American also living in Germany. Her blog is no longer up, but her recipe was really good. I've changed it a bit over the years and I'll do my best to share it with you here.
Red Eggs at Easter symbolize the blood of Christ and His resurrection. Many traditions have developed around the egg, such as dyeing and decorating the eggs, playful egg cracking competitions, as well as blessing them and receiving them on Pascha.
I love making red eggs with onion skins. I like the natural process and the thrifty New Englander in me loves reusing my onion skins and saving money. If you don't start collecting your new batch of skins like I do after Pascha (I fill a grocery bag as I remember throughout the year) you can go to a grocery store and ask for skins or pick some out of the onion produce bin. Get yellow onion skins, they work the best.
The ideal proportion is 1 cup packed onion skins per 1 cup water. My basic recipe is:
5 cups packed yellow onion skins
1/4 cup white vinegar (per 4 cups water)
5 cups water
4 dozen eggs. You can dye more or less but this is a good start. (I prefer starting with brown eggs, but white works too)
Start by putting your onion skins in a large stew pot or dutch oven. Put just enough water in so the onions are submerged. Turn the stove up to med/high. I like to place a plate over my skins (as pictured) to make sure they are fully submerged and all color is released. Boil for as long as it takes for the dye bath to turn a deep red/orange. I always strain and remove my onion skins as I find leaving them allows for lines and marks on the eggs. Allow the water to cool a bit and add the vinegar.
Next put as many raw eggs as fit into the bottom of your pot in the dye bath. Don't worry about adding more water, as you add eggs the level should rise and cover all the eggs. The eggs will cook as they dye. Bring the water to a boil and let the eggs cook for 8-10 minutes. I check my eggs at this point. Normally this is enough time and the eggs are a deep red. If for some reason they are not you can take the pan off the heat and let the eggs darken in the water for a few more minutes.
When the eggs are to your liking, remove them and let them cool on a plate. Once they are cool rub them with a paper towel or cloth dipped in olive oil. This gives them a beautiful shine and I like to think it helps to set the dye.
Repeat with the rest of your eggs.
If you want to save your dye for more fun, keep it in a jar with lid. Last year we collected a bunch of early Spring flowers and ferns. We used old tights to keep the greenery tight against the hardboiled egg. We made it simple and just put the individual eggs to dye in a jar. You could also put them in a pot together and heat the dye. Our dye was cold and we let the eggs sit for an hour. They were a special addition to our basket last year.
Source. God is love and the source of all that is good. The bounty and the beauty of nature, the light in our souls, and the beginning of dreams all flow from this goodness.