Take one onion, chop finely, place in a frying pan with olive oil and add 1 finely chopped clove of garlic and 1 tsp dried basil. Saute this then add 1 can of italian tomatoes. Bring to a boil, season to taste, then simmer for at least 1/2 an hour to render it down. It thickens itself. Place it in the processor and blend till smooth.
This can be frozen.