Bring a large pot of water to a boil. Rinse and dry the tomatoes and cut out the stem. Score an "X" into the bottom of each tomato.
Set up an ice bath - a large bowl filled with cold water and ice.
Add the tomatoes to the boiling water and boil for 1 minute. Remove from the boiling water and transfer to the ice bath. Let cool for 2-3 minutes, just until they're cool enough to handle.
Peel the skin off the tomatoes from the "X" that you scored. Place peeled tomatoes into a food processor. Pulse a few times to break them down, but not turn them into liquid. Drain any excess liquid.
Pour out the water from the pot you used to boil the tomatoes. Add the olive oil, garlic and onion and cook over medium heat for 3 minutes, until just softened and fragrant. Add in the crushed tomatoes, lemon juice, sugar, basil, parsley salt and pepper.
Bring to a boil, then reduce to a simmer. Simmer for 45 minutes, stirring occasionally.
To Can the Tomato Sauce
Place a trivet in the bottom of a large stockpot and fill with 12-16 cups of water (you want the water to be 1 inch overtop the largest jar you are canning.) Bring to a boil.
Pour the tomato sauce into the prepared jars, place the lid on top and seal.
Carefully lower the filled jars into the boiling water, using tongs. Boil for 35-45 minutes, then use the tongs to remove the jars from the water. Place them onto a kitchen towel to cool.
When the jars make a popping noise, they have properly sealed. Store them in a dark place for up to a year/ (Canned tomatoes can last longer if not exposed to light or heat, but this is an average time frame for quality tomato sauce)
Recipe Time does NOT include the initial sterilization of the mason jars. If your lids do not pop: You can still eat the tomato sauce. If using within a week, transfer to the fridge. If not, transfer to a different container and freeze for up to 3 months (mason jars can crack in the freezer). Nutritional Data is based off 1.5 cups (12 oz) of sauce (approximately the sauce used to in a 3-4 person recipe serving)