This section is from the book "Preserving And Pickling", by Mary M. Wright. Also available from Amazon: Preserving and Pickling: Two Hundred Recipes for Preserves, Jellies, Jams, Marmalades, Pickles, Relishes and Other Good Things.
Choose the small silver-skinned variety. Peel and place overnight in a brine that will float an egg. In the morning drain. Put over the fire to boil enough vinegar to cover the onions and about one teaspoonful each of allspice and cloves to each quart of onions. Fill the onions into the jars, adding, a few small red peppers, then pour over them the scalding hot vinegar and seal A tablespoonful of sugar added to each quart of onions will improve these for many. If preferred, cook the onions until tender before placing them in the jars. Either way will make good pickles.