Boil the sauce. Then reduce the heat to medium and simmer, uncovered, for 4 hours, stirring occasionally. The surface of the sauce should make a little gravy. The sauce is ready when it thickens well (depending on the type of tomato and the heat of the fire, the cooking time may vary. Cook to the desired consistency).
Remove the bay leaves. Put in sterilized jars while the sauce is still hot. When cool, tighten lids and freeze jars. To consume, take a day in advance and put in the refrigerator. It will melt slowly and retain all its texture and flavour.
Enjoy !