Here is my updated process for tomato sauce. I've been canning sauce for about 20 years and I am still working on my technique.
This batch comes from Osage Farms, my favorite farm stand, just north of Clayton.
I start by taking the stem connectors out of the tomatoes (Romas) and cutting them in half. I then cook them on the stove for a few minutes. Once cooked, I can drain off excess water. The longer you cook tomato sauce, the more acidic it gets. Draining water helps reduce the cooking time; the water is pretty clear so it doesn't take out much flavor. This step also loosens the skins which I can pick off with a fork.
I also sweat some onions.
I throw everything into the crock pot. For a long time, I cooked my sauce on the stove, which required me to do the Italian grandmother thing and tend the pot. The crock pot is much easier---I don't know why it took me so long to figure this one out. And the batch I can fit in my crock pot is five quarts, which is a pretty good fit with my canner. I cook for about four hours on low.
I then pack it into quart jars and process it in the pressure cooker. This is my second box of tomatoes this year, yielding a total of 20 quarts. That is enough to keep me content until the next harvest.