A salt water bath mellows the strong flavor of fresh onions. Raw onions have a strong flavor from the sulfur compounds they emit when cut. Soaking the onions in an ice water bath keeps the onions crisp. Adding salt to the bath also adds flavor to the onions. When the onions are soaked, the water absorbs the sulfur from the onions. After 30 minutes, your onions will be ready to use, with a more mellow flavor for raw use.
Combine 1/4 teaspoon of salt for every 1 cup of water needed to cover the onions in a bowl.
Add ice to the bowl.
Submerge the sliced onions in the water for 30 minutes.
Drain the onions through a colander and rinse before using in your recipe.