I bought tomatoes at the Amish market last weekend dreaming of fresh tomato sauce in the dead of winter. But then I had to get them to that usable stage in this miserable heat.
This is a very easy way to do that. No peeling or seeding, just cook the diced tomatoes with some onions and garlic and seasonings of your choice. Put it all in a slow cooker and cook for a long long time. I had to use my big old Nesco slow cooker and I cooked them uncovered set on 220 for 24 hours.
Then I use my stick blender to puree the whole batch. I added fresh basil and let it simmer for a couple more hours stirring it occasionally. Don't cover it!
Place 1 tablespoon of lemon juice in each sterilized jar and fill them with sauce leaving 1/4 inch of space at the top.
Place them in a boiling water bath making sure the tops are covered by 2 inches of water. Cover and let them bubble away for 35 minutes. Turn off the burner and let them sit for 5 minutes then remove them from the pot and let them rest on a towel until you hear them all seal. Mine sealed before I took them out of the water bath.