Tomato pasta sauce

6 tomatoes,
1 onion,
a pinch of salt,
2 tubs of passata,
a teaspoon of olive oil,
and a bit of ketchup.

Chop up the tomatoes and put them in a large pot to cook on a low heat for 30 minutes and whilst they are cooking chop up the onions and when the tomatoes are finished cooking add the onion and olive oil stir place the lid on top turn the heat up and leave for 5 minutes until onions are partially see through pour in the passata, ketchup, and salt bring to a low boil and leave for 20 minutes.