128-140 oz. crushed tomatoes
1 large onion, diced
1 bulb garlic, roasted and smashed
2-3 T. olive oil
1/4 cup kosher salt
1 T. dried oregano
1 T. basil
1 tsp. parsley
1/4 tsp. red pepper flakes
1/2- 1 cup sugar
For canning:
Quart jars, lids, and rings (of the same brand)
Jar tongs
Pressure canner
Lid magnet
Ladle
Jar funnel
Prepare your garlic.
In a large pan on medium low, sweat your onion until translucent.
Add the sauce ingredients, sugar, and seasonings. If the sauce is already somewhat thick, add 1 cup water. Add the garlic once it's ready.
Cover pan with a splatter screen and simmer for 30 minutes to 2 hours, stirring periodically and checking the flavor, or until desired consistency. If you cook it down too far to get at least 3 quarts, stir in some broth for extra flavor and to make enough.
Possible add ins:
Mushrooms, zucchini, carrots, peppers, celery, extra onion, or ground meat. Cook with the onions.
Refrigerate for 2 weeks or can for months.
Canning:
Read the instructions for your own canner if you do not have the same one; these are for a Presto with a pressure gauge.
Clean your sink and drain plug with soap and water and rinse thoroughly. Put your jars, rings, jar funnel, and ladle in the sink and fill with very hot water. Put the lids in a small pot of water and bring it just to a boil.
Put your canner on the stove, make sure the platform is in the bottom and fill it with at least 3 quarts of water. Turn the heat on medium low and let the water get hot.
Line your jars up. Using the funnel, ladle hot sauce into the jars up to just a bit under the first ring. 
If you get any sauce on the jar rim, clean it off. Put on the lids using the lid magnet and screw on the rings just until barely sealed, you should be able to easily loosen them again.
Use jar tongs to lower the jars into (no more than 5) the canner. The water should come about half way up the jars. If it doesn't, add more.
Seal the canner and bring the pressure up to 11. Adjust the heat as needed to keep it there. Process for 15 minutes (70 minutes if you added meat to your sauce).
Turn off the heat and let the pressure drop on its own. Carefully open and use the tongs to move the jars to trivets or a heat safe surface. Leave until the jars have completely cooled to the touch. Tighten the rings.
Push on the centers to make sure they've all sealed. If any still pop, they will need to be refrigerated and used within two weeks. The sealed jars can be safely stored in the pantry for several months. After opening and using the sauce, discard the lids. They will not seal again.
If you want to, you can re-process the unsealed jars once. Pull off the lids and clean them with soap and water. Wipe the jar rims. Boil the lids and re-place. Put on the rings and can as you did before. If any still don’t seal, you’ll need to refrigerate them.
*You can use a combination of plain sauce, crushed tomatoes, tomato paste, diced tomatoes, whole peeled tomatoes, or fresh chopped tomatoes, depending on what you have available. Put any chunks or dices though a food processor until smooth if you don't want chunky sauce.