In a saucepan add the item which is the source of the dye (e.g. beets, spinach, etc). There is some personal discretion with the amount:for more dye or darker dye, use more of the item.
Add water to the pan to reach 1 inch over the top of your dye source. Bring the water to a boil then reduce to a simmer.
Simmer the mixture until the water is the color you would like for your dye. NOTE: The eggs will be lighter than the dye so bear this in mind when choosing how dark the dye is.
After having reached the desired color, carefully strain the dye mixture into a glass measuring cup and discard the dye source material (e.g. beets, spinach, etc). Add 1 tablespoon of white vinegar per 1 cup of liquid.
Allow the mixture to cool before adding eggs to avoid cracking.
Let the eggs soak until desired color is achieved. NOTE: I immersed mine in dye in the afternoon and put them in the fridge overnight.
Remove eggs from the dye and put them in an egg carton to dry.