Mince the garlic using a garlic press.

Chop the cucumbers, onions, green pepper, and red pepper using a food chopper.

Combine the chopped vegetables and minced garlic in a large bowl.

Drain any excess liquid from the vegetable mixture.

Sprinkle 1/3 cup of pickling salt over the vegetable mixture.

Let the salted vegetable mixture stand for 3 hours to draw out moisture.

Drain the vegetables thoroughly after the 3-hour salting period.

In a large pot, combine the vinegar, sugar, mustard seeds, and celery seed to create the brine.

Bring the brine to a boil over medium-high heat, stirring until sugar is dissolved.

Pour the boiling brine over the drained vegetables.

Return the mixture to a boil.

Carefully transfer the hot relish into sterilized jars, leaving appropriate headspace.

Seal the sterilized jars according to standard canning procedures.