Instructions

1. Sterilize the jars and lids in advance and let them fully dry on a clean kitchen towel.
   
2. While the jars are drying, wash the tomatoes, cut them in half lengthwise, and remove the stems.
   
3. Use a spoon to remove the seeds and juice from the tomatoes.
   
4. Place the tomatoes in a pot, cover, and cook over low heat, stirring often, until they are soft (about 20 minutes). Add a bit of salt at the end and mix well.
   
5. Once soft, pass the tomatoes through a food mill. If the sauce is too liquid, reduce it over low heat until it reaches the desired consistency.
   
6. Pour the tomato sauce into the dry jars, leaving 2 cm (about 1 inch) from the top. Add basil to taste, if desired.
   
7. Seal the jars tightly and process them in boiling water for 40 minutes.