A simple tomato sauce,
Fry a chopped onion in some olive oil, ( preferably) although rapeseed is good, add crushed garlic , either one of two, sprinkle some salt over to stop it burning , when soft add the tinned tomatoes , crush them if they are whole, add a good squeeze of tomato puree and some dried oregano and chillies , and a splash of balsamic vinegar ,simmer for about 20/25 minutes on a very low heat, if it is a bit dry add some water, I usually wash out the tin and use a bit of that. You can serve this with pasta , gnocchi are lovely or you can serve with pan fried salmon or cod or chicken.