Start by preparing all of your materials: start a large pot of water boiling for skinning the tomatoes; start the water boiling in your canner; clean your jars and boil your rings and lids; fill the sink with cold water and add some ice cubes; set your lemon juice and salt handy along with a Tbsp and tsp measure.
Wash your tomatoes under running water.
To remove the skins, dip the tomatoes in boiling water for 60 seconds - I usually do 6-7 tomatoes at a time. Be sure to allow the water to come back to a boil before adding the next tomatoes.
After boiling for 60 seconds, place the tomatoes in the ice water to stop the cooking - we only want to loosen the skins, not cook the tomatoes. I prefer to boil all of the tomatoes and giving them time to cool before proceeding.
The tomato skins should be split in the water, if not you can cut them in half and the skin should peel off easily.
If using Roma tomatoes, you can just trim off the stem end. If using other tomatoes, you will want to remove the green core from the tomato.
You can preserve the tomatoes as whole, halves, chunks or diced. We prefer chunks so I cut them in half lengthwise, and then in half again to make long quarters - then I cut these into chunks.
Put the tomatoes into jars and use a spoon to pack them tightly into the jar. Leave 1/2" of head space.
Add the lemon juice and salt to each jar.
Process for 90 minutes in a boiling water batch, or 25 minutes in a pressure canner at 11-15 pounds of pressure.