Sterilize your jars - Fill your water bath, and add the empty jars. Boil for 10 minutes to sterilize the jars. Add your tongs, ladle, and strainer to the boiling water to sterilize as well.
Prep veg (small dice) - Peel, deseed, and chop the cucumber - you need 2 quarts of chopped cucumber. Skin and chop the onion. Destem and deseed the peppers, and chop - you need 1 quart of of chopped onions and peppers.
Soak the veg - Combine the chopped veg in a large bowl, sprinkle with the salt, and cover with cold water. Let stand for 2 hours. Rinse and drain thoroughly.
Make the brine - Combine the sugar, spices, and vinegar in a large saucepot. Bring to a boil. Add the vegetables and simmer for 10 minutes.
Pack the jars - Using a slotted spoon, pack the hot relish into sterilized jars, leaving 1/4 inch headspace.
Process - Process 10 minutes in a boiling-water bath. Let rest for 5 minutes off the heat before removing the jars from the water.