I do a simpler sauce with pips in. Gently cook chopped onion and garlic to taste in olive oil.....
You add cooked onion, I don't, I sieve pips out, you don't.
One's called sauce one's called passata. Absolutely gorgeous whichever method you use
I think the secret is simmering them for much longer than you'd think, to get that really thick texture and real tomatoey taste. Yum yum!
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Note 1: You can't be sure that tomato sauce/passata put into jars will keep more than a week or two, unless you waterbath them. Simple heat sealing, as for jam, is not reliable for tomatoes.
2: You should not add any more veg to these recipes (eg peppers/chilli/aubergines) if you want to bottle them. It is the acid in the tomatoes which is preserving them. If you want to add extra veg then you must freeze it, or add when heating through to serve.
I'd hate anybody to get an upset tum and blame me