This is a very basic sauce - you can add celery, carrots or peppers to it during the initial cooking, vary the herbs or zing it up with some chilli, but I find it is more versatile made quite plain. That way it can be used in a wide range of different dishes, from curries to pasta sauces, as a soup base or even a pizza topping, simply by adding different ingredients to it when you use it.
Start with 2 kg tomatoes and two large onions. You will also need 4 cloves of garlic, some Herbes de Provence and a squeeze or two of tomato purée.
Slice the onions and place in a large pan with 500ml cold water and about half a teaspoonful of dried Herbes de Provence. Roughly crush the garlic (I just give it a bash with the flat of a heavy knife) and add it to the pan. Halve the tomatoes across their "equator" and squeeze each half over a bowl so the seeds drop out. Leaving them in will make your sauce bitter and watery. However you don't need to skin them as the skins will be sieved out later. Slice the halves and add them to the pan. Don't add any seasoning yet.
Now cook the whole lot very slowly for at least a couple of hours until everything is disintegrating. Once it is cooked, push it through a fine nylon sieve to remove the skins and any remaining lumps of onion. You can get even more of the lovely pulpy sauce out of the mixture if you use a Mouli-legumes with the finest disc in it.
Once it is all sieved, return to the rinsed out pan and, if your tomatoes are on the pale side, add a little tomato purée to improve the colour. I found this year's tomatoes didn't need any. Now boil hard until your sauce is very reduced and concentrated. If your freezer is as full as mine at this time of year, you'll want it to be as thick as possible so it takes up the smallest amount of space - you can always dilute it when you use it! This is why I prefer not to season it - I like to do that when I am using it as i know then how much I am diluting it.
Finally pack in freezer boxes and don't forget to label it (speaking from experience - it looks very like dhal when frozen).
I like to have some home made pesto that has been frozen in ice cube trays in the freezer. A tub of tomato sauce warmed up with a cube of pesto in it makes a delicious almost-instant sauce for pasta. And one of these tubs has been earmarked for use in a stuffed marrow.
I'm joining in the Simple and in Season link-up at Fabulicious Food