This is a recipe to make in the summer — for winter. I use whatever tomatoes I have that are ripe and sweet, usually a blend of Romas and cherry tomatoes, with a few heirlooms thrown in. If you are using tomatoes other than Romas, expect the sauce to be pretty wet, unless you cook it down for a long time. I like to drain off excess tomato water — which I drink chilled or work into another recipe — so I don’t have to cook the sauce for a long time. I’d rather have a slightly runny sauce that tastes of fresh tomatoes than a thick sauce that tastes of cooked tomatoes.

This quantities specified are open to variation; feel free to tweak the sauce to your taste. The only real necessity? A food mill.

Steps

1. Begin by preparing the tomatoes: Remove the cores and pare out any blemishes, worm holes, or moldy streaks. Quarter large tomatoes and halve Romas, but leave cherry tomatoes whole.
2. Get out a couple of large sauce pots and a large baking sheet; cover the sheet in foil and a film of olive oil. Divide the tomatoes between the pots and the sheet, placing the tomatoes on the sheet cut-side down.
3. Preheat oven to 375 degrees. Put the tomatoes in the pots on the stove and bring to a boil, then turn down to a rollicking simmer.
4. Toss the garlic cloves, onion quarters, and red-pepper halves with a splash of olive oil, then spread out on another foil-covered, large baking sheet. Place both baking sheets in the oven; put the tomatoes on the lower rack and the mixed vegetables above.
5. Check the roasting vegetables often; if the tomatoes are emitting a lot of juice, drain the juice (reserving it for another use) and continue cooking the tomatoes until they are shriveled, browned, and blistered, about 30 to 45 minutes. Cook the other vegetables until the garlic is soft and the peppers and onions have begun to darken around the edges, anywhere from 45 to 90 minutes. (The garlic may take only 45 minutes, the peppers an hour, and the onions even longer.)
6. Meanwhile, depending on how juicy your tomatoes are, and whether or not you siphon off the juice, the tomatoes on the stove will take anywhere from an hour to two to cook. Be sure to give the pot a stir now and then, scraping down the sides and checking to make sure that the sauce is not sticking to the bottom of the pots. As the sauce gets thicker, turn the heat down to a more gentle simmer.
7. Once the stove-top sauce is the thickness you like, turn off the heat. Squeeze the roasted garlic into the sauce, as well as the cooked peppers and onions. Add the blistered tomatoes, give everything a stir, and then leave the sauce to cool.
8. If your food mill has more than one sieve, drop in and attach the one with small or medium-sized holes, then set the mill over a bowl. Once the sauce has cooled, spoon several ladles of it into the mill. Rotate the handle of the food mill, passing the sauce under the blade and through the sieve. Stop occasionally to scrape the pulp from the bottom of the sieve into the bowl, being careful not to tip the skins and seeds into the bowl as well. Once you have milled all the sauce, add the basil and season to taste with salt.
9. Ladle the sauce into the freezer bags until the bags are half-full. Press out extra air and zip shut. Continue until you have filled as many bags as you have sauce. Store in your freezer, laying the bags of sauce flat, one on top of the other. Once they are frozen through, you can line them up vertically if this eases the space squeeze in your freezer.