Prepare the tomatoes. Start by blanching your tomatoes to remove the skins. Cut a small "x" on the bottom of each tomato and immerse them in boiling water for about a minute until the skins begin to peel away. Transfer them to an ice bath to cool.
Crush the tomatoes. Once cooled, peel off the skins, remove the seeds, and crush the tomatoes by hand or with a food mill.
Cook the garlic. In a large pot, heat the olive oil over medium heat. Add the minced garlic and sauté until fragrant, about 1 minute.
Add tomatoes. Stir in the crushed tomatoes and tomato paste. Mix until the paste is evenly distributed.
Add seasonings. Add the basil, oregano, salt, pepper, sugar (if using), and bay leaves. Bring the mixture to a simmer.
Simmer. Reduce the heat to low and let the sauce simmer uncovered for 2 to 3 hours, stirring occasionally, until it reaches the desired consistency for pizza sauce.
Prep for canning. While the sauce simmers, heat your mason jars. Wash the lids and bands in hot soapy water, the place them in hot water so they're ready when you need them.
Add lemon juice. When the sauce is ready, remove the bay leaves and stir in the lemon juice.
Fill jars. Ladle the hot pizza sauce into the hot mason jars using a funnel, leaving ½ inch of headspace.
Wipe jars and apply lids. Wipe the rims of the jars with a clean cloth to ensure a good seal. Place the sterilized lids on the jars and screw on the bands until they are fingertip tight.
Process. Process the jars in a boiling water bath for 35 minutes.
Cool. Once the jars have been processed, remove the canner from the heat and let the jars sit for 5 minutes. Then use a jar lifter to carefully remove the hot jars. Place them on a cloth in a heat-safe area to cool for 12-24 hours. You should hear a 'ping' sound of the jars sealing.