In a large bowl, combine the sliced cucumbers, onion, and ½ cup salt. Mix to incorporate and pour into a large colander. Set inside a large bowl for 3 hours to drain excess water.
1 gallon sliced cucumbers, 3 medium onions, ½ cup canning salt
After 3 hours, discard the drained liquid. Rinse the cucumbers and onion well and allow to drain.
Prepare the water bath, 8 pint jars, lids, and rings.
In a 4-quart kettle, combine the vinegar, water, sugar, turmeric, cloves, celery seed, mustard seed, red pepper flakes, and 2 tsp salt. Stir to dissolve the sugar and bring to a boil. Reduce to a simmer while preparing the cucumbers in jars.
3 cups vinegar, 1 cup water, 1 ¾ cup sugar, 1 ½ tsp turmeric, 1 ½ tsp whole cloves, 2 tsp celery seed, 2 tsp mustard seed, ½ tsp red pepper flakes, 2 tsp canning salt
Pack jars with rinsed and drained cucumbers and onions, leaving ½-inch headspace. Pour brine over prepared cucumbers and onions, still leaving that ½-inch headspace. Wipe the rims of the jars with a clean cloth to remove any drips. Place on lids and rings, tightening to fingertip tightness.
Place jars in the boiling water bath. Bring back to a boil and boil for 10 minutes. Check with the USDA canning guide and adjust the process time for altitude.
Remove from the water bath and cool for 12-24 hours. Remove rings to ensure a good seal and store for up to one year.
Food safety tip: This recipe may not be approved by the USDA. To prevent the risk of botulism, always check with the USDA Canning Guide.