Selecting: Tomatoes come in a variety of sizes and shapes, but in all cases select ripe, firm tomatoes that are unblemished and well-shaped. Don't use any tomatoes with spots, cracks, or those that are overripe, soft, or decayed.
Preparing: Allow 2½ to 3 pounds tomatoes for each quart or about 1 pound for each pint. Thoroughly wash and remove stems. Put tomatoes into a wire-mesh basket. Dip into boiling water in a large kettle or Dutch oven for 30 seconds (water must be kept at or near boiling). Remove from boiling water and immediately dip tomatoes into cold ice water. When cool, slip off the skins and remove cores and stem ends. Pack small or medium tomatoes whole, but cut large tomatoes into quarters or eighths. Use a small spoon to scrape out excess seeds, if desired. Pack tomatoes as tightly as possible into clean jars, leaving a ½-inch headspace. Use a wooden spoon to press tomatoes gently till the juice runs out and fills the jar with no air pockets. Add 1 teaspoon salt for quarts or ½ teaspoon for pints. Wipe jar rims; adjust lids. Process in boiling water bath for 45 minutes for quarts or 35 minutes for pints (start timing when water boils).
Follow these ten guidelines:
1. Wash jars and lids in hottest cycle of dishwasher to sterilize. Or wash the jars in hot sudsy water and rinse thoroughly and pour boiling water over jars and let them stand in hot water until ready to fill.
2. Prepare tomatoes as indicated above.
3. Pack tomatoes into jars, leaving the headspace indicated above and add salt. A cloth placed under the jar prevents it from slipping and catches any spills while filling the jars.
4. Release any air bubbles in the jar by gently working a wooden spoon or other non-metal utensil down the side of the filled jar.
5. Wipe off the rim of the jar with a clean, damp cloth or paper toweling. Any bits of food on the rim could prevent a perfect seal.
6. Add the lids and boil jars covered with water for the specified time.
7. Remove processed jars to a rack to cool. Allow air to circulate around jars, but keep the area free of drafts.
8. After jars are completely cooled, check for a seal. To test jars, press the center of the lid on a cooled jar. If the dip in the lid holds, the jar is sealed. If the lid bounces up and down when pressed, the jar isn't sealed.
9. If a jar isn't sealed, check it for flaws. Repack and reprocess the contents using a clean jar and a new lid for the full length of processing time. Or, refrigerate the food and use it within a day or two.
10. Label and store the jars in a dry, cool, dark place.
This article courtesy of The Chef's Garden