This is clearly a summer canning recipe for pickled zucchini relish. It might be good, although I haven’t tried it myself. You will need a large crock or other type of container to hold the relish as you are making it. It also will need to be properly canned, and while it doesn’t indicate the yield, you are starting with 14 cups of zucchini/onions. These will mush down during the process, but be prepared for a large quantity of relish.
Grind (coarse) unpeeled squash to make 10 cups. Grind onions to make 4 cups. Place both in bowl with 4 Tbsp salt. Let stand in fridge overnight. Drain in AM and let water run through it 3 times. Drain well — add 2 1/2 cups vinegar – 3 3/4 cups sugar, 1 tsp nutmeg, 2 tsp mustard seed, 1/2 tsp black pepper. Grind 1 large green and 1 large red pepper. Combine all ingredients in kettle and place on burner. Stir gently. Bring to boil and cook for 3 minutes. Put in jars and seal.