Start Your Water Bath Canning: Fill your water bath canner with hot water (enough water to cover the size of jars you are using), and place on your stove at medium-high heat and bring to a boil.
Clean Jars: Wash jars with warm soapy water. Place the jars into the canner to sterilize while it comes to a boil.
Prepare Your Tomatoes: Wash tomatoes under running water, ensuring all of the dirt and debris is removed.
Dice the Tomatoes: Use a sharp knife to dice the peeled tomatoes into your preferred size for canning diced tomatoes. Aim for uniform pieces.
Add Lemon Juice or Citric Acid: For quart jars, add 2 tablespoons of bottled lemon juice or 1/2 teaspoon of citric acid to each jar. This ensures the required acidity level for safe canning. You can also add 1/2 teaspoon of salt for flavor. For pint jars, add 1 tablespoon of lemon juice, or a 1/4 teaspon of citric acid to each jar.
Fill Jars with Diced Tomatoes: Using a canning funnel, pack the diced tomatoes into your clean, hot jars, leaving about a 1-inch headspace from the top of the jar. You want to really pack down your tomatoes to let the juices out.
Remove Air Bubbles: Use a bubble remover tool or a plastic knife to remove any air bubbles by running it along the inside of the jar.
Wipe Jar Rim: Wipe the rims of the jars with a clean, damp cloth or paper towel to ensure a good seal.
Heat and Apply Lids and Bands: Start a small pot of water and place your lids to heat. Once the lids are warm, place the clean lid on each jar and secure it with a band, tightening it until it’s fingertip-tight – not too loose, not too tight.
Process Jars in a Boiling Water Bath Canner: Place the filled jars in the canner load, ensuring they are covered with at least 1 inch of boiling water.
Process for the Required Time: Quart jars should be processed for 45-50 minutes, and pint jars for 40-45 minutes (adjust for altitude if necessary). Make sure the jars are continuously submerged during processing. Add more boiling water if needed to maintain the water level.
Remove and Cool Jars: After the processing time, use a jar lifter to carefully remove the hot tomatoes from the canner. Place them on a clean towel or cooling rack, leaving space between them to cool and get to room temperature.
Check for Seals: As the jars cool, you’ll hear the satisfying “pop” of lids sealing. Check for seals by pressing down in the center of each lid. If it doesn’t pop back, it’s sealed. Store sealed jars in a cool, dark place.
