Preheat your oven to 300 degrees F. Heap the tomatoes into your largest roasting pan (or divide them into two separate pans). Drizzle them with the olive oil and sprinkle 1 tablespoon of kosher salt over the top. Stir to combine.
Roast the dressed tomatoes for 45 minutes to an hour, until they crack and soften. I like to get a little bit of dark color on the skins for flavor. Do make sure to give them a stir every fifteen minutes or so.
When the tomatoes are sufficiently softened, remove the pan from the oven and let them cool a bit.
Once the tomatoes are cool enough that you won't get a burn if a bit of juice lands on your skin, fit your food mill with its medium-sized screen and start working them through.
Pour the pulped tomatoes into a pan and bring it up to a low boil. Add the sugar (start with 2 tablespoons and add the third only if you feel the sauce needs it), Italian spices, the remaining salt, and black pepper and stir to combine.
Simmer, stirring often, until the sauce has cooked down by about 1/3 and doesn't seem at all watery.
Prepare a boiling water bath canner and enough jars to hold about five pints (I like to can my pizza sauce in half pint jars, because that's typically how much we use on pizza night).
Measure 1/4 teaspoon citric acid into your half pints and 1/2 teaspoon citric acid into your pints.
Funnel the finished sauce into the jars, leaving 1/2 inch headspace. Use a wooden or plastic chopstick to stir the citric acid into the finished sauce.
Wipe the rims, apply the lids and rings, and process in a boiling water bath canner for 30 minutes.
When time is up, slide the pot off the hot burner, remove the lid from the canner and let the jars cool slowly for five minutes.
Remove jars from canner and set them on a folded kitchen towel to cool.
After 24 hours of cooling, check seals. Jars that have sealed can be stored in the pantry. Any unsealed jars should be refrigerated and used promptly.