Part One
MIX & PULSE tomatoes, onions, and bell peppers in a blender, food processor, or grinder. You'll have to do this in small batches. The ratio is two tomatoes to every one onion and half of a bell pepper.
DRAIN - Place the vegetables in a colander to drain, and add salt. If you chopped them small, place a cheesecloth on the bottom of the colander. Let sit for one hour to drain fully.
POUR your freshly strained mixture into a large stock pot on high heat. Mix in the sugar, vinegar, mustard seed, and celery seed.
BOIL - Bring the mixture to a boil. Once it begins to boil, reduce the heat down to a simmer and then cook uncovered for thirty minutes. The goal here is to thicken up your relish by boiling off the liquids. Stand by and frequently stir to avoid scorching.
SERVE immediately, refrigerate, or can the relish in a hot water bath.
Part Two - Canning Instructions:1. Carefully place the jars of green tomato relish into the water bath canner, making sure that at least two inches of water covers the tops of the jars.