The result is a loss of some of the heat without a loss of flavor. With the harshness gone, you can use these onions raw in salads or sandwiches. Cover them with equal parts vinegar and water, and you can store them for up to two weeks in the refrigerator. Or freeze chopped onions in ziplock bags. Don't use a food processor for chopping onions.
Processors release so much juice that the onions' crisp texture is lost.
Before chopping onions, refrigerate them for several hours. If they are very cold, their compounds are less volatile, and consequently, less irritating. To dice onions, cut a thin slice off the stem end and remove the outer layer of skin. Halve the onion through the root end and lay flat side down. When you slice down through the layers, the onion will fall into pieces.