Q: I’ve just read your instructions [for canning chicken stock]. I’ve tried twice now to can a batch of stock in my pressure canner and most of the jars won’t seal. I removed air bubbles, left 1″ in the jar, and followed the other instructions. Any ideas why these jars won’t seal?—Jen

A: After Jen asked me this, we had a long e-mail discussion about the various options. She was indeed doing everything right, but we eventually settled on two things. First, her stock was fairly fatty. While this makes for delicious stock, it can make getting a good seal more difficult if fat gets trapped between the lids and the jar. But secondly, and more importantly, this was a case of opening the pressure cooker lid too soon.

But what, exactly, constitutes “too soon”? Most pressure canning instructions, including mine, tell you to wait about 10 minutes after letting the pressure drop of its own accord before opening the lid. Over time, though, I’ve found that this is too soon. A pressure canner full of chicken stock is very, very hot. Even when the pressure drops inside the canner, the temperature and pressure inside the jars is still quite high. The dramatic change in pressure from removing the lid (even after the indicator has fallen) can be enough to cause liquid to spurt or seep out of the jars. This not only causes you to lose some of your precious chicken stock, but it also interferes with the seal. So now, whenever I pressure can anything with a significant amount of clear liquid (beets, tomatoes, stock, etc.), I always wait at least an hour after the pressure drops before opening the lid. Ideally, I do this at night and just turn off the heat and go to bed. The next morning, I take off the lid, and viola! Everything seals.

Jen e-mailed me about a week later with an update. Success!

Can I just tell you how delicious this yellow mole is, and how grateful we should be that Rick Bayless exists to tell us hopeless gringos how to make such things? You really, really must make this. Besides being absolutely delectable, it’s a great use for frozen green beans! Heavens! This version turned out especially well because I used fresh, extra fatty chicken broth. I’m sure it’s still good and will do less damage to your arteries if you skim your stock. Warning: four guajillo chiles (pictured below) were too much for me. Two were too few. So, um, use three, or to taste?

Chicken with Yellow Mole (paraphrased and ever-so-slightly adapted from Rick Bayless’s Mexican Everyday)

3 dried guajillo chiles, stemmed and torn into several pieces
1 pint roasted tomatoes
1/2 small white onion
2 cloves garlic, peeled
1/2 t. ground cumin
4 c. fresh chicken broth
2 T. canola oil
2 c. cooked chicken (if you’re making broth, bingo! you’ve got chicken!)
1 T masa harina, or coarse cornmeal in a pinch
2 c. green beans (frozen are fine)
2 large or 4 small Yukon Gold potatoes, cut into 1″ pieces
Salt
Cilantro

1) Combine the torn chiles, tomatoes, onion, garlic, cumin, and 1 cup of the stock in a blender. Puree until smooth.

2) Heat up the oil in a large, heavy pot. Add the tomato-chili mixture and cook until it looks like a thick paste. Rick says it takes about 5 minutes; I needed closer to 20. Maybe that’s because I’m using about twice the tomatoes that he recommends. In any case, dragging a spoon through the mixture should leave a track.

3) Whisk the masa harina or cornmeal into the remaining stock, then add that to the chile-tomato mixture. Bring to a boil and simmer until it starts to get thick. Add the cooked chicken (ideally shredded), the green beans, and the potatoes. Cook until the potatoes are tender, then taste and adjust the seasonings.

Serve with warm tortillas. Hint: if it’s too spicy, eat it with yogurt. This gets better and better as it sits in the fridge, though I doubt it will last that long.

And if you don’t have a pressure canner, don’t despair. Just freeze it.

Step 1: Make the Stock

Don’t be intimidated by stock: it is, after all, the basis of peasant cooking everywhere. All you really need is either a chicken or a chicken carcass and some aromatics. Carrots, celery, onions, garlic, and parsley are traditional, but you can use cilantro, tomatoes, peppercorns, turnips, ginger, or anything else that tastes good boiled. Don’t add anything that gets bitter or otherwise nasty as it boils, like cabbage, broccoli, or eggplant.

Just toss your odds and ends into a pot, add a few quarts of water, and let it cook for awhile. If you’re using a regular stovetop pot, you should probably let it simmer about an hour. Since I tend to make my stock with leftover bones, I like to use the pressure cooker to extract as much flavor as possible: 12 minutes at 15 pounds pressure. Next, strain the liquid and let it cool for several hours or even overnight. The fat will form a solid layer (see right) that you can skim off, if desired.

Step 2: Can the Stock

I know, I know: this is where people get nervous—and rightly so. Canning low-acid foods can be a dangerous business, but it’s perfectly safe if you follow a few simple steps.

1. Heat up the stock, and use clean jars. Start with clean, sterilized jars. Garden variety commercial jars may not be strong enough to stand up to the temperature and pressure of canning. For this, you want real Mason jars. Meanwhile, heat the stock to near boiling.

2. Heat the lids. While you can reuse the rings, it’s important that you use new lids every time you can. This is because the rubber ring on the lid is not guaranteed to work more than once. It might, but is the risk of botulism worth it? Spend the $1.99 and buy yourself another dozen lids. Soften the rubber and sterilize the lids by heating (but not boiling) them for about 10 minutes.

3. Transfer the stock to the jars, and screw on the lids. You can buy a canning funnel designed especially for regular-mouth jars—it’s totally worth it. For pressure canning, you should leave 1″ headspace. The lids should be screwed on fairly tight.

4. Transfer the jars to the pressure canner. A large pressure canner, like one pictured here, can hold up to 7 quart jars. Be sure to use the rack so the jars don’t break. Next, add 2 quarts of boiling water to the canner. A note to experienced water-bath canners: it is NOT necessary to cover the jars! You just need 2 quarts or so to produce enough steam to raise the pressure to the proper temperature.

5. Seal the canner and evacuate the steam. This is an easily overlooked, but important, step. Close and lock the lid and turn on the heat to high, but don’t add the pressure regulator yet.  After a few minutes, you’ll see a jet of steam coming out of the central valve.

It’s a little hard to see in this picture, but trust me, it’s there. Let it go for about 7 minutes, then add the pressure regulator.

6. Cook at pressure. Most canning guides suggest 25 minutes at 10 pounds of pressure for quart jars, and 20 minutes for pint jars.

7. Let the pressure drop of its own accord. Then wait another hour or so before opening the canner. Even at this point, the contents of the jars may still be shockingly hot, so be very careful before reaching in there. You’ll want to use tongs or potholders to remove the jars from the canner.

8. Cool and store. This is the easy part! Let the jars cool completely, label, and store in a dark place. Do make sure that they’ve sealed: if the lids are springy, they didn’t, and you should refrigerate or freeze them instead. But honestly, with pressure canning, everything seals, every time.