Most of the relishes and other condiments at the grocery store contain a lot of white vinegar. This can be a problem if you are allergic to the corn that most white vinegar is made from. It's also a problem if you are seriously allergic to yeast, as traces of yeast are likely to remain in vinegar. These marinated onions, besides being vinegar-free, have a citrusy tang and a tamed onion flavor that make them an excellent all-purpose relish.
1/4 c. fresh squeezed grapefruit juice (See Juice in the Glossary)
1/4 c. fresh squeezed lime juice (See Juice in the Glossary)
1 large mild red onion
salt (See Salt in the Glossary)
Stir the grapefruit juice, lime juice and 1 tsp. of salt together in a bowl. Slice the onion into very thin strips (see the illustration below). Move the onion to the bowl; stir. Allow to steep at room temperature for 20-30 minutes, stirring occasionally. Adjust salt to taste. Refrigerate.