Combine all ingredients in a large, non-reactive pot. Bring to a boil and then reduce temperature to a simmer. Stirring regularly, cook at a low boiluntil it reduces to a sticky, jammy mess. This will take between 1 and 1 1/2 hours, depending on how high you keep your heat.
When the jam has cooked down sufficiently, remove from heat and fill jars, leaving 1/4 inch of head space. Wipe rims, apply lids and twist on rings. Process in a boiling water canner for 20 minutes.
When time is up, remove jars from water bath and allow them to cool. When jars are cool enough to handle, test seals. Store jars in a cool, dark place for up to one year.
*The finished yield on this recipe varies depending on the kind of tomato you use, the width of your pan and the finished thickness to which you cook it.