Sprinkle cucumbers, onions & peppers with pickling (course) salt and water. Let sit for 4 hours. Drain - DO NOT RINSE.
In a stockpot, mix brine ingredients and bring to a boil. Add drained vegetables and continue cooking until it has returned to a boil.
Add paste to boiling mixture and cook until thick. NOTE: You can add some green food colouring before adding the paste for a greener relish.
Place your canning jars in a large canner with enough water to cover them by at least 1-inch, and bring to a boil. Boil for at least 10 minutes. Also place your lids in a pan of simmering water, and simmer for 10 minutes. This ensures that the jars and lids are sterilized before adding the relish to them.
Lift the sterilized jars from the boiling water bath and empty them. Half should be emptied into the sink, and half should be emptied back into the pot to keep the boiling water level up.
Once the relish mixture is hot, fill each jar with relish, to within 1/4" of the rim. Wipe the rim clean with a paper towel dipped in boiling water, and place the lids and rings on top of the jar. Return the jars to the boiling water bath and boil them for 10 minutes, well covered in water.
Remove from waterbath and set jars on a dry towel, free from drafts. Allow to cool completely before checking that each jar has sealed (the lid is pulled down slightly, and no longer “pops” when you push on it). Label and store in cool, dark place. It is best to used home canned goods within 12 months.
Recipe by Faithfully Gluten Free at http://www.faithfullyglutenfree.com/2008/09/homemade-relish.html