1. Prepare tomatoes by quartering and cooking. While you can process/pulp tomatoes while raw, using the hot method results in a more emulsified sauce.
2. To cook, stir, or mash some of the tomatoes to release juice, and heat over medium heat, stirring occasionally.
3. Bring to a simmer, and cook through.
4. Remove from heat, and process through your food mill to remove skin and seeds. If using a popper or Victorio-style strainer, you may need to reprocess the seed and skins multiple times to remove all the pulp.
5. Place deseeded pulp in a large stock pot, and bring to a simmer.
6. Allow to simmer until pulp is reduced to desired thickness. This usually takes a few hours.
7. When desired thickness is reached, remove from heat.
8. Into each prepared canning jar, add lemon juice and salt – 1 tablespoon of juice, and 1/2 teaspoon salt per pint, or double those amounts for quart jars.
9. Ladle sauce into jars, leaving 1/2 inch headspace
10. Wipe rims clean, and screw down lids and bands firmly

To water bath can:

1. Prepare canner with hot water, and ensure that the rack is inside.
2. Place jars in canner, leaving a little space between each jar so they won’t jostle and break while boiling.
3. Add more water if needed to completely cover jars.
4. Place lid on canner, and bring to a rolling boil.
5. Process quart jars for 40 minutes, or pint jars for 35 minutes.
6. Remove from heat.
7. Let canner cool significantly, then remove jars to finish cooling. Be careful to protect yourself from hot jars, and keep jars covered until they are cool to touch.
8. After 24 hours, check seals and store in a cool place out of direct light.

To pressure can:

1. Prepare canner. For a 16 quart canner, this usually means adding 2 quarts of water, making sure the rack is inside, and making sure the seal on your lid is good, and the valve doesn’t have any clogs.
2. Arrange jars of sauce in the canner, and lock the lid in place, with the valve open.
3. Heat until a steady stream of steam escapes the valve.
4. Let steam for 10 minutes.
5. Close valve, and bring to 10 pounds of pressure.
6. Process both pints and quarts for 15 minutes.
7. Remove from heat and let return to zero pressure naturally
8. Wait several minutes more, and carefully remove hot jars, covering them with a towel as you remove them. Protect yourself with the towel in the unlikely event that one should break and splatter.
9. Let cool completely.
10. After 24 hours, check the seals, and wash if needed before storing in a cool place out of direct light.