Step 1

To prepare tomato puree from frozen tomatoes: (assuming they were cleaned and cored before freezing) leave to thaw 24 hours; drain accumulated juices and put through a strainer to remove seeds and peels.

Step 2

To prepare tomato puree from fresh tomatoes: wash, core and halve tomatoes; heat to boiling (I use a 12-quart stockpot and a 6-quart soup pot for 22 pounds); put through a strainer to remove seeds and peels.

Step 3

Make the pizza sauce: in a 12-quart or larger stockpot cook onions and garlic in the olive oil over medium heat until the onion softens, 5-10 minutes. Add tomato puree and all the seasonings (basil through pepper flakes), bring to a boil, reduce heat and cook for about 30 minutes, uncovered. Process with an immersion blender to make a smoother sauce (or carefully blend in batches).

Step 4

Bring back to a boil; reduce heat and simmer, uncovered, until sauce reaches desired consistency (reduced by 1/4 to 1/3), usually an hour or two, depending on if you started with fresh or frozen tomatoes. Make sure to stir occasionally to prevent sticking (if you have a thin-bottomed stock-pot, stir more often to prevent scorching).

Step 5

To can: add the lemon juice or citric acid to each clean, warm jar, fill jar with sauce leaving 1/2-inch headspace and attach lids and rings until fingertip-tight. Place in canner rack and repeat with remaining jars to fill canner (keep sauce and jars warm, as you will need to do a couple canner loads when using half-pints).

Step 6

Process both pints and half-pints for 35 minutes in a boiling-water canner (find more details in our Canning 101 steps found in the recipe index).

Step 7

Remove to a towel-lined surface and let sit undisturbed for 24 hours before checking seals, labeling and storing in a cool, dark place.