In my family, we never used artificial colored dyes.
Instead, we took the leftover onion peels in the pantry, wrapped them around the eggs and boiled them.
The downside of this is you do need to plan in advance a little as you need to have raw eggs and you end up coloring them while you hard boil them. If the eggs are cooked, you really can't do this unless you want to cook the eggs again. You also have to have a sufficient quantity of onion peels laying around.
The basic steps are:
- Wet everything down
- Wrap the egg in the onion peel.
- Secure it with a rubber band
- Hard boil the egg.
Depending how you wrap them, you'll end up with a very nice marbled look that varies in color depending on what kind of onions you use. We typically have yellow onions, so I know the will give you a red-brown color. I have never tried it with any other color of onion, so I can't speak for the coloring with them and if it would be any different.