Combines chopped cucumbers, onions, and peppers in a large bowl.
Sprinkle with pickling salt and stir to distribute the salt throughout the mixture.
Add enough cold water to cover the vegetables
Cover and allow to stand for 2 hours at room temperature.
Transfer vegetables to a colander set in the sink.
Rinse with cold water and allow to drain.
In a large stainless-steel or nonsitck pot, combine sugar and vinegar.
Heat to boiling, stirring until the sugar dissolves.
Add the mustard seeds, celery seeds, and turmeric to the solution along with the chopped vegetables.
Return to boiling, reduce heat, and simmer for 10 minutes, stirring occasionally.
Ladle the hot relish into hot, sterilized canning jars, leafing a ½ inch headspace.
Wipe the rims, add the lids and screw bands.
Process the filled jars in a boiling-water canner for 10 minutes.
Remove the jars from the canner, place on a dry towel, and allow to cool overnight.