Heat a good glug of olive oil in a medium saucepan. Choose a saucepan with a tight fitting lid. When the oil is hot add the passata. Stand back as it will spit a bit. Stir the sauce for a few minutes and then put the lid on. Keep the sauce on a medium low heat for about five minutes. Keep a check on the sauce as it can catch on the bottom. After five minutes add a little butter and swirl it through. This adds a bit of richness to the sauce but is not necessary. Cook through a few more minutes, taste for seasoning and add a bit of salt and peper to taste. Sometimes I add a pinch of sugar, just to even out the acidity. Serve over pasta with grated cheese (Parmesan or Cheddar). For an extra special treat serve with Pizza Express Style Dough Balls
To freeze, leave the sauce to cool down completely and pack into small plastic containers. It is generally not a good idea to put something acidic like tomatoes in something metallic as it may give the sauce a tinny edge.
Passata is Italian pureed tomotoes. You will find this in most supermarkets now, Waitrose, Sainsbury's and Tescos stock it. If you can't find this you can use normal tinned tomatoes and then put them through a sieve. This will add to the preparation time, but you will still get a really tasty sauce.
Maldon Sea Salt is my preferred salt. You can use ordinary table salt instead. I like the Maldon's soft flakes and it's "saltiness" which means you probably end up using less. It is also a very natural product, which means it's better for you......end of advertisement, I promise I don't own shares in this company.