Even pickle devotees will be fooled into thinking you’ve used cucumbers.
Sprinkle the zucchini, onions, and garlic with salt, and cover with cold water. Let stand 2 hours. Drain, rinse in fresh cold water, and drain again. Combine the remaining ingredients in a large pot and boil 5 minutes. Add the vegetables, remove the pot from heat, and let stand 3 hours. Return the pot to a boil and simmer 5 minutes. Pack pickles into sterilized jars and process 10 minutes in boiling water.