Prepare your tomatoes by washing in plain water. Cut them in half or quarters and add to your saucepots.
In a large frying pan, sauté onions and garlic in olive oil until softened, about 5 to 7 minutes.
Add the onion mixture to the tomatoes, and bring the pot to a simmer over low heat. As the tomatoes cook, they will release their juices. Stir occasionally to prevent sticking and continue simmering until the tomatoes are soft, about 20 minutes.
After the tomatoes and the vegetables are soft, turn off the heat and allow the sauce to cool.
Run the cooled tomato sauce through Food Strainer or Food Mill to remove skins, seeds, and to smooth out the sauce.
Return the strained tomato sauce to the saucepan(s) to cook down further to thicken the sauce. Add oregano, bay leaves, pepper, sugar, and crushed red pepper. If you are using multiple pots, roughly divide the ingredients for each pot. All the ingredients will be combined into one pot as the sauce cooks down. Simmer over low heat with the cover vented so the excess moisture evaporates. As the sauce reduces, combine it into one pot. Use your ladle to avoid splashing.
Once the volume is reduced by half, your tomato sauce should be nice and thick. Use a clean spoon and taste the sauce. Add salt and stir in. Taste again. Add more salt if needed. Keep the sauce warm over low heat.
Prepare your jars and lids by washing in warm, soapy water and rinsing thoroughly. Place jar rack into water bath canner, set jars in the canner, add water, and boil jars for 10 minutes to sterilize. Warm your lids in a small pot over low heat. Keep jars and lids warm until ready to use.
Spread a kitchen towel on the counter. Use your jar lifter to remove warm jars from canner, drain, and line up on the towel. Add citric acid or bottled lemon juice to each jar. For pints, add 1/4 teaspoon of citric acid or 1 Tablespoon of bottled lemon juice to each jar. For quarts, add 1/2 teaspoon citric acid or 2 Tablespoons of bottled lemon juice to each jar.
Use your canning ladle and funnel and add tomato sauce to warm jars leaving 1/2-inch headspace. Wipe the rims. Use your magnetic lid lifter to lift lids out of the warm water, center lid on the jar, and screw on band until it is fingertip tight.
Using a jar lifter, place jars carefully into canner leaving space in between them. Once jars are all in canner, adjust the water level so it is at least one inch above the jar tops. Add more boiling water if needed so the water level is at least one inch above the jar tops. When adding water, use the hot water from the small pot your lids were in. Pour the water around the jars and not directly onto them.
Cover the canner and bring to boil over high heat. Once water boils vigorously, process pints for 35 minutes and quarts for 40 minutes at altitudes of less than 1,000 ft. (adjust processing time for your altitude if necessary - see notes below).
When processing time is complete, turn off heat and allow the canner to cool down and settle for about 10 minutes. Spread a kitchen towel on the counter; remove the cover by tilting lid away from you so that steam does not burn your face. Use a jar lifter to lift jars carefully from canner and place on the towel. Allow the jars to cool for 12 to 24-hours. You should hear the satisfactory “ping” of the jar lids sealing.
After 12 to 24-hours, check to be sure jar lids have sealed by pushing on the center of the lid. The lid should not pop up. If the lid flexes up and down, it did not seal. Refrigerate jar and use up within a few days.
Remove the screw on bands and wash the jars. Label and date the jars. Store your jars in a cool, dark place and use within 12 months. Yields about 6-7 pint jars or 3-4 quarts depending on how much the sauce reduces.