Prepare Tomatoes: Wash the tomatoes thoroughly under cold running water.Bring a large pot of water to a rolling boil. Blanch tomatoes in the boiling water for 30-60 seconds, then immediately transfer them to a bowl of cold water. Peel the skins, core the tomatoes, and remove any bad spots.
Prepare Jars: Wash your jars, lids, and screw bands in hot, soapy water. Keep jars warm in your canner or oven until ready to fill.Add 2 tablespoons of bottled lemon juice to each quart jar (use 1 tablespoon for pint jars). Add 1 teaspoon of salt per quart jar (use 1/2 teaspoon for pint jars).
Pack Jars: Pack the tomatoes tightly into the jars, leaving 1 inch of headspace at the top.Pour boiling water or tomato juice over the tomatoes to cover them, still maintaining 1 inch of headspace.Use a non-metallic spatula to remove any air bubbles by sliding it around the inside edge of the jar.
Seal Jars: Wipe the rim of each jar with a damp cloth to remove any residue.Place the lids on the jars and screw on the bands until fingertip tight.
Process Jars: If using a boiling-water canner, ensure the water level is 1 inch above the tops of the jars. Bring to a steady boil and process quart jars for 45 minutes (adjust for altitude if necessary). Pint jars should be processed for 40 minutes.If using a pressure canner, process jars according to the manufacturer’s instructions, adjusting for altitude.
Cool and Store: Once the processing time is complete, turn off the heat and let the jars sit in the canner for 5 minutes.Carefully remove the jars with a jar lifter and place them on a dry towel. Allow the jars to cool at room temperature for 12-24 hours without disturbing them.Check the seals after cooling. If the lid does not flex up and down, the jar is sealed. Store sealed jars in a cool, dark place. If any jars did not seal, refrigerate and use them within a few days.