Step 1: Thoroughly wash canning jars, lids, and bands in hot soapy water. Sterilize jars by simmering them in hot water (at least 180°F / 82°C) for at least 10 minutes. Keep jars hot until ready to fill. Place lids in hot, non-boiling water (around 180°F / 82°C) until needed.
Step 2: Fill your water bath canner halfway with water and bring it to a simmer (180°F / 82°C).
Step 3: Wash fresh tomatoes under cold running water. Remove stems and core, cutting out any tough parts or blemishes. Score a shallow ‘X’ on the bottom of each tomato.
Step 4: Bring a large pot of water to a rolling boil. Carefully immerse a few tomatoes at a time into the boiling water for 30-60 seconds, or until the skins begin to crack. Immediately transfer them to an ice bath to stop the cooking process.
Step 5: Once cooled, easily peel the skins from the blanched tomatoes. You can discard the skins or save them for a future project (like making tomato powder).
Step 6: Crush the peeled tomatoes. You can do this by hand, using a food mill for a smoother consistency, or by coarsely chopping them. For a thicker product, you may wish to remove excess seeds, though it’s optional for crushed tomatoes.
Step 7: Transfer crushed tomatoes to a large stockpot. Bring to a gentle simmer and cook for 10-15 minutes, stirring occasionally, to reduce some liquid and release trapped air. This prevents separation in the jars and improves consistency.
Step 8: To each hot, sterilized quart jar, add 2 tablespoons of commercially bottled lemon juice or 1/2 teaspoon of citric acid. Add 1 teaspoon of canning salt (if using). For pint jars, use 1 tablespoon lemon juice or 1/4 teaspoon citric acid, and 1/2 teaspoon salt.
Step 9: Ladle the hot crushed tomatoes into the prepared jars, leaving 1/2 inch of headspace from the rim.
Step 10: Use a non-metallic utensil to gently remove any air bubbles trapped in the tomatoes. Press the utensil down the sides of the jar, allowing air to escape. Adjust headspace by adding more tomatoes if necessary.
Step 11: Wipe the rims of the jars clean with a damp paper towel. Place a hot lid on each jar, followed by a band, tightened just to fingertip-tight.
Step 12: Carefully place the filled jars onto the rack in the simmering water bath canner. Ensure water covers the jars by at least 1-2 inches. Add more hot water if needed. Cover the canner and bring the water to a rolling boil.
Step 13: Once boiling, begin timing. Process quart jars for 45 minutes and pint jars for 40 minutes. Adjust processing time for altitude (consult a reliable canning chart for your elevation).
Step 14: After processing, turn off the heat and remove the canner lid. Let the jars sit in the hot water for 5 minutes before carefully removing them with a jar lifter. Place jars on a clean towel on your countertop, ensuring they are not touching each other, and let them cool undisturbed for 12-24 hours.
Step 15: After cooling, check for seals. The center of the lid should be concave and not flex when pressed. Remove bands, wipe jars clean, label them with the date and contents, and store in a cool, dark, dry place. Refrigerate and consume unsealed jars within a few days.