Put zucchini and onion slices through grinder or pulse in food processor in VERY SMALL batches. Mix well with salt and let stand covered, not refrigerated, overnight.
Rinse with cold water and drain well. In a large kettle, mix the sugar, spices, and constarch with vinegar. Cook until the vinegar starts to thicken a bit. Chop or grind the red and green peppers. Add them to the zucchini-onion mixture to the hot vinegar mixture and mix thoroughly. Cook slowly for 30 minutes. Can in hot canning jars at once and seal. No need for hot water bath or processing.