A sweet and savory concoction that captures all the wonderful flavors of summer.
Place all the chopped vegetables in a large bowl.
Sprinkle the canning salt on top of the vegetables and add enough cold water to cover the vegetables.
Cover and allow to stand at room temperature for 3 hours.
Transfer the vegetable mixture to a large colander in the sink. Rinse with cold water and drain.
In an 8-10 quart heavy stockpot, combine red wine vinegar, white vinegar, water, sugar, mustard seeds, celery seeds, and turmeric.
Bring to a boil and stir until the sugar dissolves. Reduce heat and simmer for 3 minutes.
Add the drained vegetable mixture to the pot and return to a boil. Reduce heat again and simmer, uncovered, for about 10 minutes, stirring occasionally.
Ladle into hot, sterilized pint jars, leaving a ½ inch headspace. Remove any air pockets, wipe rims, and apply prepared lids and rings. Tighten rings until finger-tip tight.
Place the jars in a boiling water canner, cover with water, and process for 15 minutes. Start timing the processing once the water in the canner is boiling.
Turn off the heat and let the jars stand in water for 5 minutes.
Transfer jars to a towel-lined surface and let rest at room temperature until cooled. Check seals and store in a cool, dark place.
This relish is a wonderful accompaniment with grilled meats or a plate of summer vegetables. It can also be used as a snack on top of crackers spread with cream cheese.