2) Add the celery and carrot and season with salt and pepper. Saute until all of the vegetables are soft, about 5 to 10 minutes. Add the tomatoes, basil and bay leaves and simmer uncovered on a low heat for one hour or until thick.
3) Remove the bay leaves and check for seasoning. If the sauce still tastes acidic, add some unsalted butter, one tablespoon at a time, to round out the flavours.
4) Place half the tomato sauce into the bowl of a food processor. Process until smooth. Repeat with the remaining tomato sauce.
Note: If you are not using all of the sauce, allow it to cool completely and pour 240ml to 480ml portions into plastic freezer bags. This will freeze for up to six months.