There should be no kitchen (or freezer) without this. We have been discussing how many dishes we could prepare with this sauce and have counted no less than 15 from pasta with tomato and chorizo to cod with tomato and peppers, meatballs, lasagna or peas with tomato. You can prepare 3 or 4 kilos of tomatoes at the same time and freeze most of the sauce. It lasts a couple of months in the freezer and around a week and a half in the fridge.
2 kg of tomatoes (either fresh or canned - in winter it is better with canned tomatoes anyway)
1 green pepper
1 red pepper
3 medium onions
3 cloves of garlic
1 bay leaf
you also need a hand food mill (this is very useful also for vegetable pures, mash potatoes and baby food). You can buy them for £18 at John Lewis or for £13.27 in Amazon.
Coat generously the base of a large pan. While the oil is heating cut all the vegetables into large chunks. Once the oil is hot add all the other ingredients. Let it fry for 10 to 15 minutes and then reduce the heat to its lowest setting and let it bubble for 1 to 1.15 hours. If you are using a pressure cooker you only need 25 minutes. Blend all the mixture with the hand food mill. Taste it and adjust the seasoning. If you let it bubble for the indicated time the sauce should not be acidic. However, if you think it is not sweet enough you may add a teaspoon of sugar (or even better, add a carrot next time you prepare it)
The children love getting the sauce through the mill - but beware of this because your kitchen may end up looking like a battlefield!