Using a food processor, coarsely chop the onions and peppers. Process only two at a time, otherwise they turn into paste. Mix all the ingredients in a large, heavy stockpot and cook over medium heat together until onions begin to become translucent, about 15 minutes. Prepare 8 half-pint jars, lids and rings according to manufacturer's instructions. Spoon the relish into the jars, filling to 1/2 inch from rim. Clean the rims and seal according to manufacturer's instructions. Process sealed jars in boiling water for 10 minutes.