"This is a family favorite! A simple DIY that everyone will love! This is a family recipe from my Grandma, Penny Faust. One of my favorite childhood memories was watching my mom can her sweet zucchini relish. Yum! We use it in anything from homemade dressings, potato salad, egg salad, tuna salad...etc."
Run zucchini, red bell pepper, and onions through a meat grinder. Transfer ground zucchini mixture to a large bowl; sprinkle with salt. Refrigerate zucchini mixture, overnight or at least 10 hours.
Pour zucchini mixture into a large pot; add sugar, vinegar, celery seed, and turmeric. Bring to a boil, stirring constantly, for 15 to 20 minutes. Stir cornstarch into mixture; continue boiling until thickened, about 5 more minutes.
Sterilize the jars and lids in boiling water for at least 5 minutes. Pack relish into the hot, sterilized jars, filling the jars to within 1/4 inch of the top. Run a knife or a thin spatula around the insides of the jars after they have been filled to remove any air bubbles. Wipe the rims of the jars with a moist paper towel to remove any food residue. Top with lids, and screw on rings.
Place a rack in the bottom of a large stockpot and fill halfway with water. Bring to a boil and lower jars into the boiling water using a holder. Leave a 2-inch space between the jars. Pour in more boiling water if necessary to bring the water level to at least 1 inch above the tops of the jars. Bring the water to a rolling boil, cover the pot, and process for 10 minutes.
Remove the jars from the stockpot and place onto a cloth-covered or wood surface, several inches apart, until cool. Once cool, press the top of each lid with a finger, ensuring that the seal is tight (lid does not move up or down at all). Store in a cool, dark area.