How to reheat frozen soup in bag

Full question

The recipe for Roast Squash and Sweet Potato Soup from Nigella's Christmas Kitchen (and the book Christmas, p53) is recommended for freezing. Does the soup need to be defrosted first or can it be reheated straight from frozen? Thank you.

Instead of making a giant pot of soup and eating it five days in a row like my roommate and I did in college, if you think strategically, a big batch of soup can be made exciting. Not only is soup supremely delicious and comforting, but it has an extraordinary life span—if you play your cards right.

But there are a few questions that might go through your head. Here are the answers—on freezer zip-top bags versus containers, whether certain soups freeze better than others (i.e. vegetable versus chicken), and how to salvage freezer burned soup, to name a few— so you can get to stocking your fridge for the months to come.

How Much to Freeze?

• The key to becoming a soup maker starts with always having plenty of broth or stocks in your freezer. While broth and stock sound complicated, they really are not; complex, nuanced brews can be had in under an hour, made from the scrappiest of scraps (read: compost) and water (I usually estimate 1 part vegetable scraps to 1 part water, or 1 part animal bones to 4 parts water—but feel free to alter the ratios as you your soup sees fit.)
• Freeze broth in usable portions: I’ll usually freeze in two-, four-, or six-cup containers, or divvy a stock up between ice cube trays. (Keeping broth or stock frozen in small-ish increments means, also, that you can also quickly thaw portions.)
• For both broth and soup, leave at least an inch of headspace in your container (especially if freezing in glass jars!) for the liquid to expand as it freezes.

Do I Have to Label?

Good labeling is important, because no one wants mystery food in the freezer. Using painter’s tape or masking tape, label your broth or soup with its name and the date you made it.

What Date, Though?

For soups and broths, store for up to 5 days in the fridge, except for fish soups, which can be stored for up to 3 days. For soups, store for up to 3 months in the freezer, and for broths, freeze up to 6 months.

Okay, Containers.

If using glass containers, be sure they’re made of tempered glass that can be frozen. If you’re using any type of plastic, be sure it’s BPA-free. I especially love freezing soup flat in zip-top gallon-sized bags, as I feel it’s a more efficient use of (very precious) freezer real estate. (This way, you can stack ‘em like records or sweaters.)

• Weck jars
• Ball jars (now available in tempered glass)
• Snapware or similar glass storage containers
• Zip-top, gallon-sized bags
• BPA-free plastic containers

Ready to Eat! How Do I Thaw?

You have three options for thawing:

1. If you have the time, the ideal method is to place the frozen container of soup in the fridge for two days before you want to use it. It will thaw in a day or two, depending on the size and shape of the storage container.
2. If you're in a rush, place the soup in its container in a warm water bath until it is fully thawed.
3. The in-between option is to immerse the container in warm water to loosen the frozen soups from the sides. Then pop it out directly into a pot and let it thaw over medium-low heat, stirring to keep the soup from scalding.

Avoid thawing in the microwave, especially when the soup is in a plastic container. When plastic is heated, it can potentially leach chemicals into your food. And be careful when freezing and thawing in glass jars. Make sure the glass is tempered and can handle the extreme temperature changes. When soup is frozen in glass jars, it will not pop out as easily as it does from plastic containers, so leave extra time for thawing.

How Do I Warm It So It Tastes Good?

Many soups’ solids absorb most of its liquid when stored, resulting in a thick, paste-like consistency. Simply add a half cup of broth or water to thin it back out, then taste and liven it back up with a spritz of lemon juice, pinch of salt, or even fresh herbs if needed. (Freezer-burned soups—which are totally safe to eat, but can taste a bit dull—would especially appreciate being perked by this spa treatment.)

Any Tips for Planning Ahead? (So I Actually Freeze Soup)

Make a big pot of soup, eat half, and freeze half. Next week, make another pot and do the same. Are you seeing what I’m seeing? A freezer with TWO types of delicious homemade soup ready to thaw.

And once you really get into soup making, you’ll discover that it’s just as easy to make two soups at the same time. The reality is that once you have your broth in your freezer and the rest of the makings on hand, you’re more than halfway there. Pick two soups that are like cousins; the broth is the same and maybe the vegetables are different. Maybe you’re going to blend one. Do them simultaneously on the stove, and double your soup inventory.

What Soups Don’t Freeze Well?

There are very few that don’t. Here are some things you’ll want to be careful of:

• Don’t freeze soups with starchy (rice, quinoa, or pasta) elements. Freeze the broth or liquid part apart from the solids; thaw, then add your starch. Otherwise, your soup absorbs all your liquid and becomes a gummy, starchy soup when you thaw it. Ugh!
• Sweet potato soups freeze well, but potato soups are not the most freezable because they turn gummy.
• Cream- and milk-based soups have a tendency to separate, and can become grainy. Vigorously whisking (or blending again) the soup post-thawing can help the liquid re-emulsify. Soups made with coconut milk freeze and thaw rather well!
• Does your recipe call for adding fresh herbs at the end? Freeze without, then add fresh herbs when you thaw and reheat.

Finally: Be diligent about your freezer inventory. It’s a sad day when you have to throw out bad soup, so keep an eye on those labels and eat them well before the expiration date. Keep older soups at the front of the fridge, and stash newer ones in the back.

When you have soup—whether chicken noodle, coconut-creamy lentil, or hearty vegetable—in your freezer, it’s like having gold. You never know when you’ll want to give soup love to family, friends or yourself. What a precious gift!

For more soup recipes and smarts, Rebecca's book is Clean Soups.

What's your favorite soup to keep all the time in the freezer? Tell us in the comments.

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