Wash tomatoes to remove any dirt under cold running water and then remove the core and blossom ends from the tomatoes. 

Cut tomatoes into quarters and set aside. 

Peel onion and garlic, chop and then saute in olive oil over medium heat in a large pot until the onions have softened and are translucent. 

Add tomatoes and simmer 20-30 minutes making sure to stir the tomatoes occasionally. 

Puree tomato mixture in a food mill to remove peels and seeds. 

Return tomato puree to the large pot, add minced basil and cook over medium heat {uncovered} until the mixture is reduced by half, stirring to prevent scorching.   

Fill a hot water canner about 2/3 rds full with water and bring it to a boil. 

Wash jars and screw bands in hot soapy water; rinse with warm water. Pour boiling water over flat lids in a saucepan off the heat. Let stand in hot water until ready to use. Drain well before filling.

When your sauce is ready, add 1 tablespoon of bottled lemon juice to each pint jar or 2 tablespoons of bottled lemon juice to each quart jar.

Ladle hot tomato sauce immediately into prepared jars, filling to within 1/2 inch of tops. Remove any air bubbles. 

Canning Time

Wipe the jar rims and threads clean if needed. If using traditional canning jars, cover with 2-piece lids. Screw bands on.

If using Weck jars, carefully place the Weck rubber gasket on the lid of the jars. Place the lid on the jar and secure the lid with 2 evenly spaced Weck clamps. 

Place jars on an elevated rack in a hot water bath canner. Lower rack into canner. {Water must cover jars by  2 inches. Add boiling water, if necessary.}

Cover; bring water to a boil. Process pint jars for 35 minutes or quart jars for 40 minutes. 

Turn off heat and remove jars and place upright on a towel to cool completely. Cool jars for 12-24 hours. 

After the jars have cooled, check the seals by pressing the middle of the lids with your finger. If lids spring back, lids are not sealed and refrigeration is necessary. {Traditional canning jars}. 

For Weck jars, check to make sure your seal is pointing downwards. 

Remove rings or clamps and store jars in a cool dark place. 

Yields about {7} pints or about {4} #743 Weck ¾ L Mold jars