Peel, trim and wash the carrot, onion and celery, then chop them roughly.
Put a good glug of olive oil in a 3 to 5 litre pot.
Add the vegetables, peeled garlic and bay leafs.
Put a lid on the pot and cook on a low heat for about an hour - until the veg is soft.Add the tinned tomatoes and tomato puree.
Add any fresh green herbs you have.
Add enough water to leave the vegetables just sticking above the surface.
Put a lid on the pot and cook on a low heat for about an hour.
Let the mixture cool.
Puree the mixture with a liquidiser or hand blender.
If you have one, pass the mixture through the finest disc of a food mill. It will produce a tastier sauce with a silky texture.
Store the sauce in convenient amounts in the freezer. I find 500g tubs to be about right. Use plastic storage boxes, washed butter tubs or plastic bags.