A shortcut to start you off: If you have a food processor you can just toss roughly chopped zucchini, onions, and peppers into the bowl of the processor and pulse until they’re a good size. I like mine in about 1/8 – 1/4″ pieces. If you don’t have a food processor, just chop them finely by hand.
Combine zucchini, onion, peppers, and salt in a large bowl, stirring well. Chill overnight. Place in a colander to drain; rinse thoroughly and drain again. Transfer to a large stock pot and add remaining ingredients; bring just to a boil, then simmer for 10 minutes. At this point, the relish is done. You can just put it in jars and then in the refrigerator to use right away or give as gifts.
If you’d like your finished zucchini relish recipe to be shelf stable, you’ll need to process it. Ladle hot relish into sterilized jars, leaving 1/4-inch head space. Wipe rims with a damp cloth (to assure a good seal), screw sterilized lids on, and process for 10 minutes in a boiling water bath. (Click through for a complete tutorial on water bath canning if you’ve never done it before.)
Video
Notes
Important: This is not scary. It takes about an hour to make 3 pints of relish. If you know how to operate a stove and chop veggies, you’re good to go.