This article is from the Food Preserving FAQ, by Eric Decker firstname.lastname@example.org with numerous contributions by others.
From Shona Lamoureaux ,
Taken from an impeccable source: United States Department of
Agriculture, Extension Service
16 cups fresh zucchini, sliced
4 cups onions, thinly sliced
1/2 cup canning or pickling salt
4 cups white vinegar (5%)
2 cups sugar
4 tbsp mustard seed
2 tbsp celery seed
2 tsp ground turmeric
Yield: About 8 to 9 pints Procedure: Cover zucchini and onion slices
with 1 inch of water and salt. Let stand 2 hours and drain thoroughly.
Combine vinegar, sugar, and spices. Bring to a boil and add zucchini
and onions. Simmer 5 minutes and fill jars with mixture and pickling
solution, leaving 1/2-inch headspace. Adjust lids and process
according to the recommendations in Table 1 or use low-temperature
pasteurization treatment. For more information see "Low- Temperature
Pasteurization Treatment," (HE 8220).
Table 1. Recommended process time for Pickled Bread and Butter
Zucchini in a boiling-water canner. Canner Pressure (PSI) at Altitudes
of Style of 1,001 - 6,000 Pack Jar Size 0 - 1,000 ft ft Above 6,000 ft
Hot Pints or 10 min 15 20 Quarts
This document was extracted from the "Complete Guide to Home Canning",
Agriculture Information Bulletin No. 539, USDA. Reviewed 1994.