Begin by heating olive oil over medium heat in a sauté pan. Add onions and garlic. Cook until translucent and soft, about ten minutes, stirring often.

In a large kettle, combine onion mixture, chopped tomatoes, basil, oregano, salt, and pepper. Continue to simmer over medium heat, stirring often.

After the tomatoes have begun to break down (about 30-60 minutes later), puree them. A stick blender or food mill works well. Once totally in sauce form, continue to cook down until the volume of the sauce has reduced to about one-half the original amount.

While the tomatoes are cooking down, you can begin to prepare your canner and jars if you plan on processing them. (If you want to simply place the sauce in the freezer, that’s totally okay. You can transfer it to freezer safe containers or bags and freeze once cool.)

Wash and sanitize pint or quart jars, rings, and lids. Keep warm. Fill the canner with enough water to cover the jars by at least 2 inches of water. Cover and heat on high. Watch the temperature, you want a simmer but not a boil when you place the jars in the water.

Once the sauce and canner are ready, you can begin to fill the jars. To be sure there is enough acid to have self stable jars, you must add citric acid or bottled lemon juice.

Ladle the hot tomato sauce into jars, leaving ½ inch headspace.

Wipe rims of the jars with a damp cloth, add lids and rings, tightening to fingertip tight. Place in the canner, increasing the heat to high.

Once the canner reaches a boil, process pint jars 35 minutes or quart jars 40 minutes.

Remove from heat and allow jars to cool in the canner over 5 minutes. Then remove jars from the canner, placing them on the counter.