In what's sure to become a tradition for years to come, we spent Labor Day weekend making pureed tomato sauce for freezing. Did it last year, and it was a resounding success, basically made us survive the winter without hardly purchasing any canned tomatoes. And, well, September is "Eat Local" month, and the theme's been put about that we should be focusing on conserving summer produce for winter months. Tomatoes are clearly the place to start for us.
Claudia's on the record as being wild about the stuff, and she sets a tough standard - her grandfather's pomarola. Yet, there is nothing too fancy about this. It's very easy - a bit harder perhaps when you are doing it with 20 pounds of tomatoes ... but straightforward to execute otherwise. Like with many traditional Italian recipes, time's the most important ingredient you will need.
I use a very large pan of some kind - big dutch over would work. I break the process into three phases for the twenty pounds (hence the weekend), so you could basically buy 6/7 pounds of so-called Roma tomatoes of some kind (Early Girls work, though I do prefer San Marzano). For that many, I start with one very large onion,maybe one and a half, and three or four cloves of garlic. Not too much, as you can use this in many ways, like in recipes where you might want to add additional onion/garlic. On pasta, it works just wonderfully with this quantity.
I start to saute the onion, coarsely chopped, on low/medium heat in a pretty good amount of olive oil, almost covering the bottom of the dutch over with the pour. I then add the roughly crushed/chopped garlic after about 10 minutes. No point in bothering with technique here, it'll all go in the blender eventually. While this is happening, I start to slice the San Marzano tomatoes, which I have rinsed, and shaken. As the garlic's cooked about two minutes I have about a third to a half of the tomatoes sliced, so I dump them in. I don't peel them, I don't do anything to them, just dump the lot in, sliced.
More slicing, more dumping ... the whole think takes about a half hour to do. Once you're through with the tomatoes, cover the dutch oven and cook for about twenty minutes (time is not essential here), to get the water out in the open, so to speak. Then remove the cover, and simmer for a long time. Like up to two hours, or maybe more. Stir occasionally - I put a timer on for twenty to thirty minutes. It's never enough until your sauce starts sticking. The first time I did the sauce I was working at home and forgot, and the sauce was really close to burning through.
By the end, basically, the level of your sauce will have reduced by two thirds and it will start to require some scraping as opposed to plain stirring. There'll be no more visible water, just pulp, skin, and occasional puddles of oil. If there's a bit of burnt sauce there, no worries, the blender will take care of that one, too.
Now ... scoop out into a blender, and puree thoroughly. You can let it rest for a while to cool, probably a good idea if you're going to store this stuff in plastic containers. At this stage the tomato is very very concentrated, and somewhat acid. If you were going to dress pasta with it, it would need thinning out. I do a couple of things. I puree some of the stuff as-is, and label it JT/Just Tomato on its containers. I will use this as tomato puree for things like Fagioli all'Uccelletto, or Chicken Cacciatora. The rest, I puree with some milk added. Makes it a bit more creamy, cuts the acidity down a bit, and we use this on pasta. Just add some pasta cooking water to thin out the sauce and it will be perfect.
In the containers I freeze the stuff in I add some basil leaves, to taste. To the sauce I use immediately, I add a bit of chopped basil after blending. When I picked up the tomatoes last week, my supplier was kind enough to gift me a bunch of wonderful Genovese basil, so we were all set there!
I also add a little bit of thyme in the sauce while it cooks, a nod to Provencal tomato sauces. It's doubtful that this makes a substantial difference. Bottom line, you can experiment widely with this; the point of it is the technique of cooking until bone dry, the quality of the tomatoes in the first place, and the fact that blending this you can just slice and cook the tomatoes, instead of having to peel them, which makes the prep very easy. If you're not inclined to make this in industrial quantities, just get a pound and a half to two pounds of tomatoes, and cut onion/garlic down to taste.
You can decide for yourself whether you believe this, but there's lots of stuff about how peel is good for you. Why throw it away? The blended sauce will show no trace of peel or anything, so there are no side effects from that standpoint. It's just great, wonderful tomato sauce.