Pressure-canning potato leek soup? Yes! it works!
One of the gardening joys of this Midcoast Maine “summer” has been leeks. Leeks love fog and rain and cool temps, and with enough watering during our dry spell they continued to swell in their roots, where all the action is. So my wife and I have had a fine leek season, which is now resulting in four quarts of pure velvety smooth potato leek soup (see my recipe from a previous post here).
This soup is a huge hit, hot or cold, and is savory and gentle on the palate. And for some of our family, it’s a highly anticipated Christmas gift. But if you Google “canning potato leek soup,” you will encounter a chorus of naysayers and grumpuses who tell you it’s a fool’s errand, can’t be done, the soup’s too dense, there’s too many things that can go wrong… but I’m here to say —
It CAN be CANNED! You just have to be wicked careful! And anal!
To make enough for four quarts, follow the recipe from my older post, but with these amounts:
- about 8 fat juicy leeks, washed and sliced
- 3 1/2 quarts chicken broth
- about 7 cups peeled and diced yellow potatoes – about 7-8 small ones, or 5-6 large ones
- 6 tablespoons unsalted butter
● After everything’s cooked, combine the sauteed leeks, broth, and potatoes in a stockpot, then spoon into a food processor (we use the “Ninja,” a fine machine!) and blend until silky. Return the blended soup to the stockpot and keep on very low heat.
● Now wash 4 quart jars, new (unused) lids, and rust-free bands in hot soapy water, rinse well, and set aside.
● In another large stockpot, fill with enough hot tap water to cover the 4 quart jars, and heat the water and jars to about 180 degrees. Do the same for the lids and bands, but in a smaller pan, and make sure the water doesn’t boil (it’ll ruin the lids).
● Get your pressure canner ready. Put in about 3 inches of hot water, and turn the heat on.
● Using a jar lifter, remove and drain the quart jars one at a time, and using a funnel, fill with the soup, leaving 1 inch headspace. Make sure there’s no soup goo on the outside of the jar’s rim! If so, wipe clean. Remove a lid and band, and hand-tighten. (Some directions say “finger-tight,” but I can tell you from experience you will have a disaster on your hands unless the bands are quite tight!) Place the four filled jars into the canner, cover (making sure the lid is as level as possible), and turn the heat up full.
● Once the petcock (valve) sends out a steady stream of steam, let it blast away for 10 minutes.
● Now put on the pressure gauge weight at 10 lbs. When the gauge reads 10 lbs (240 degrees), lower the heat until the pressure and temperature stay consistently at these levels, and set your stove timer to 80 minutes (some say 75, some say 85, for quarts, so I split the difference). If the gauge weight rattles every 8-10 seconds or so, you’re right on the money.
● After 80 minutes, turn the heat off. Let the pressure return to zero without removing the gauge weight – about 10-12 minutes. The whole idea here is ☛ gradual increases and decreases in pressure and temperature.
● When it’s at zero, remove the gauge weight. Wait another 10 minutes.
● Now open the canner cover, loosening the wing nuts at the rear first. Lift the rear of the cover to keep steam away from your face. Leave the jars in the opened canner for another 10 minutes. You should hear one or two of the lids snapping down into place – all of them if you’re lucky.
● Remove the jars with a jar lifter and set on a clean dishtowel several inches apart. The lids should all snap down within 5-10 minutes or so. If this doesn’t happen, something got messed up, and you’ll have to either eat or freeze the soup.
Leakage: even with very snug bands, leakage can happen. If it’s a tiny amount – say, an ounce or less – you’re okay. If it’s more than that, empty the jar and either eat or freeze the soup.
Also, the bands will loosen during canning. Don’t tighten the bands after canning – the seals could be disrupted. In fact, the Ball people tell you to remove the bands entirely from the jar, but I don’t bother.
If (despite all your best efforts) you open a jar of soup a few months after canning and it smells like something died, I don’t have to tell you what to do.
UPDATE (partly in response to some comments):
● The main reason for canning this soup is 1) to use our 100 or so leeks before they rot, 2) not to freeze the soup, because freezing affects its texture, and 3) to give these cans away as Christmas gifts, and for us that means shipping them through the mail. Yes, otherwise we’d make and eat the soup fresh.
● You can’t can a low acid food like this soup in a hot water bath; this is all about pressure canning.
● I have a call into the preserving experts at Ball and Jarden Home Brands in Indiana. They haven’t tested this particular soup, but I’m awaiting response from their (apparently) top canning expert. If they have any reservations at all, I’ll delete this post!
There you have it.