Sam and Julia have asked me before for a basic tomato sauce recipe - so here we go.
6 cans diced tomatoes (796 mL)
6 onions, peeled & quartered
1 head garlic, peeled
1 1/2 tbsp herbs (I have a mix I made which is equal parts parsley, basil, oregano, salt, and crushed chilli peppers, plus about a half part broken bay leaves)
Cook on high for about 12 hours. The first 5 hours or so cook the onion & garlic, and the next chunk of time is to reduce the liquid (I leave the lid off for the second phase). I use this for pizza, so I don't want it runny. If you are using it for pasta, you could just check it and stir it and call it ready whenever you are happy with the consistency after 5 hours. Use a soup blender thingie to blend until smooth. If you don't own one then you'll have to chop everything before putting it in.
Makes about 4-5 litres. I canned it the next day (9 x 500mL plus about 750mL leftover - but I also used a couple extra cans tomatoes because I added too many herbs by accident, augh!).
OR... If in a hurry, combine 1 can diced tomatoes, 1 diced onion, and about 3 cloves garlic (Magic Bullet or by hand) and about 1/2 tsp mixed herbs - bring to a boil, lower to medium, and let simmer till reduced to desired consistency. I don't *recommend* the fast way, but when you realize last-minute that you have no sauce for the pizza you were about to bake, it works.