Rinse tomatoes and core them. Drop tomatoes in a pot of boiling water for one minute.
Scoop tomatoes out with a slotted spoon and place in a bowl of ice water. Now the skins will slip off easily.
Cut in half (quarters for larger tomatoes) and push out the seeds out with your thumb.
Add the tomatoes and all the ingredients (except baking soda) to slowcooker.
Cook on low for 10 hours or high for 7 hours. Stir occasionally if possible. The sauce should be reduced by about half.
If you want a less chunky sauce, pulse it a few times with an immersion blender or mash it a bit with a potato masher or large spoon. Add the canned tomato paste at this point if you'd like a thicker sauce.
Add the baking soda (it will foam a bit), salt and pepper, and additional herbs to taste.
Making this all day and then refrigerating it overnight gives it an extra kick of awesome in the flavor department.You can freeze this sauce in a wide mouth canning jar. Make sure to leave 1 inch of space between the top of the sauce and the top of the jar to allow for expansion during freezing.