This is the first time I’ve tried the cold packed method. I’ve always felt it was safer when the ingredients were very hot before placing into the hot sterilized jars. But I really wanted to have whole tomatoes that were still firm. Cooking the tomatoes even just long enough to heat them through still breaks them down a bit. So I gave cold packing a try. Of course, there is still a hot liquid that gets poured over top … in the one recipe I saw, I was surprised that it called for boiling water to be poured over the tomatoes in the jars. I did not want to dilute the flavour of the tomatoes, so I cooked some of the tomatoes and pureed them to make a hot tomato sauce for this step.
As always, if you are a beginner, I highly recommend you check with someone who has more experience in this – there can be health hazards if safe canning techniques are not followed. When I open a jar months from now for some recipe, I'll be sure to give them a good smell first to make sure something didn’t go wrong (out of hundreds of jars over the years, I’ve only had 3 or 4 that were bad and it was pretty obvious!).
Sterilize jars. I wash them with hot soapy water, rinse, then keep them in a warm oven (170 degrees F) for at least a half hour before filling them.
Remove the skins first. Take out the core with a paring knife and remove any obvious blemishes. Slice an X into the bottom of the tomato. This will help the peel pull away. In batches, dunk the tomatoes into boiling water for about 60 seconds. Remove immediately and run under cold water or plunge into an ice bath. When cooled, the skins should easily peel off.
In the meantime, prepare your hot tomato sauce (assuming you equally do not want to use water). I just cooked a pot full of tomatoes for about a half hour to allow them to break down naturally, then pureed with an immersion blender (I didn’t bother removing the skins from these ones since they are being pureed).
Place peeled tomatoes into sterilized jars and follow with a ladle of hot tomato puree. Add about 1 Tbsp of lemon juice. Use the end of a wooden spoon to give a quick stir and remove air bubbles. Top up the rest of the jar with tomato puree leaving about 1” headspace.
Quickly wipe around opening of jar to ensure it is clean and allow for a tight seal. Then apply a heated lid (heated in simmering water) and screw on the band keeping it a bit loose. Process in a hot water bath for approximately 30 minutes.
And then the waiting … do not fiddle with the lids until the jars are completely cooled. Then poke the top. If the centre of the lid is already down, then it should be fine. But if the centre pops down when you push on it, then it was not sealed properly (in that case, contents should be refrigerated until used or process again if you have another batch going). Tighten all of the bands before storing in a cool, dry location.