Bring a large pot of water to a boil; meanwhile, prepare a large bowl of ice water. With a paring knife, core tomatoes, and score an X on the bottoms. Working in batches, carefully lower tomatoes into boiling water; when skins begin to split (30 to 60 seconds), use a slotted spoon to transfer tomatoes to ice water.
When tomatoes are cool, remove skins (use a paring knife, if necessary), and discard. Halve tomatoes. Remove seeds with a spoon, and discard. Finely chop tomatoes.
In a Dutch oven (or other large pot), heat oil over medium-high. Add onion and garlic; season with salt and pepper. Cook, stirring frequently, until onion is soft, 4 to 5 minutes. Add tomato paste; cook, stirring, until slightly darkened, 1 to 2 minutes.
Add tomatoes, and stir to combine. Bring mixture to a boil; reduce heat to medium-low. Cover, and simmer, stirring occasionally, until thick and saucy, about 1 1/2 hours. Season with salt and pepper. Use immediately, or freeze in airtight containers up to 3 months. Thaw at room temperature or in microwave before warming.
I added a bay leaf, oregano, and parsley. I also only used about 8 fresh tomatoes and two cans of tomatoes to make up for it. After I let it simmer for about an hour, I pureed half in a blender. I paired this with roasted chicken thighs (http://www.marthastewart.com/recipe/roasted-chicken-thighs) and poured it all over linguine. Awesome!!
Mmm... good!! I had just picked 25 tomatoes from our garden and needed a good recipe to use them up. This one is perfect! I added oregano, basil, parsley, and dried green/red peppers to the sauce. I didn't worry about getting all of the tomato seeds out. The fresh garden tomato flavor is delicious and has a beautiful earthy presentation! I doubled the recipe and filled 4 freezer bags with 3-4 cups of sauce each.