Where Can You Use Onion Skins in the Kitchen?

An onion’s outer skin forms as the outermost layers thin and dry to a papery texture while the bulb matures and dries. This layer cannot be chewed and does not soften when cooked, so it is removed before the onion is chopped. But the skin contains a natural coloring pigment: brown onion skins give hot water golden and copper tones, while red onion skins leave a darker, reddish color. The skin’s entire value in the kitchen lies in this coloring; to use it, you only need to know what the coloring is good for.

The most common use is in meat and vegetable stock. Add a few onion skins to a pot of water and let them color it as it cooks; the water deepens from pale yellow to dark gold. The skins add little flavor, so the purpose is color, not taste; use more skins for a darker color. At the end of cooking, strain out the skins along with the liquid and discard them. Cooking the skins for too long can give the water a slight bitterness, so you can remove them early once the color is dark enough.

The skin’s color does not suit every dish. Do not use onion skins in cream soups that should stay white or in light-colored sauces; they color the liquid and muddy the dish’s appearance. Skins added to the water for rice or bulgur lightly tint the grains yellow; that is welcome at some tables and not at others. Let the appearance of the dish guide the decision. Add salt and spices separately to water used with onion skins, because the skins carry color, not flavor, and do not change the water’s taste on their own. If using them for rice, boil the skins separately in water and add only the colored liquid to the rice; do not let pieces of skin get mixed into the rice.

The same property is used to dye eggs. Boil onion skins in a pot of water, and when the water has taken on a dark color, boil the eggs in it; the more skins you add, the darker the eggs will be. If you place a small leaf or a sprig of parsley on an egg and wrap it tightly in a thin cloth, the area under the leaf stays lighter and forms a pattern. The dye stays on the outside of the shell, so the egg is eaten as usual; color can seep inside if the egg is cracked.

Wash onion skins before using them. Onions are bulbs pulled from the ground and dried, and their outer skins carry dust and dirt. Swish the skins in a bowl of water and drain them. Set aside skins that are darkened, moldy, damp, or softened; use only dry, intact skins. Collect skins removed while chopping onions in a dry container, because damp skins can mold. Add them to the pot on the day you make vegetable stock, along with the other scraps; that way, a handful of skins from each onion does not go to waste.