Best eaten raw or only slightly cooked. The natural juices allow these naturally sweet onions to cook rapidly, so they should be used to enhance foods where they can be quickly sauteed or grilled.
Walla Walla onions have a shorter shelf life than common varieties due to higher water and sugar content. Thus, it’s important to store them properly. Ideally, sweet onions should be stored in a cool, dark, dry location and spread out for optimum air circulation. We suggest you try placing onions in a clean pair of pantyhose, with knots tied in between each onion, then hung in a cool, dry place. Just snip off below each knot when you need one. If stored properly, sweet onions should last in your pantry 1 month.
For raw cut onions, tightly wrap them and refrigerated to be used within a few days. For freezing, you can chop onion and place in a freezer bag. Onions in the freezer can last of to 12 months before they lose flavor.