The Conundrum of Conserving at Costco

And next week in London!

London, here I come! Join me next Tuesday, February 10 for a live recording of Cooking the Books! And then on Wednesday, February 11 for an evening of conversation and food at Honey & Co.! And then an evening with Bee Wilson at Quince Bakery on February 12!

Now to this week’s question—

Dear Tamar:

I am passionate about making use of all my produce—letting no scrap go to waste. (My family teases me that I must have been raised during the Great Depression. Few comments have made me prouder.) I’m stumped, however, when my big bins of Costco spring mix start to go bad. I try to prevent it by eating my spring mix quickly and keeping a paper towel in the bottom of the bin. But sometimes these methods are insufficient (because, I suspect, the lettuce was less than fresh when I purchased it.) I hate to throw it out. Any advice on what to do with these decomposing leaves? I’ve considered adding them to soup, as I have heard you recommend with other lettuces, but they get smelly so quickly that it doesn’t seem wise or appetizing. We purchase other, heartier lettuces as well but my husband is picky about salad and really prefers spring mix. Please advise!

-Conserving at Costco

Dear Conserving at Costco,

I remember watching my mother pluck what was pompously called mesclun (spring mix in French) with tongs from bins. No other mothers served mesclun, and I found it very sophisticated, and did the same when I had my own kitchen and my own mind.

It was years before it occurred to me, over a similar bin at the Gourmet Garage on 7th avenue (RIP), that the cut edges of the young greens I automatically grabbed were as often as not tawny brown, and the tenderest of them had a battered aspect—less freshly plucked from the garden, more survivor of an extreme weather event. The more I thought about it, the more sense it made: By definition, spring mix leaves were picked immature, unprepared to suffer the slings and arrows of harvest and storage. Their susceptibility to decay was encoded in their existence as tender baby greens.

I stopped buying spring mix from those bins. Even when the combination of baby leaves became so popular that they could be found in protective plastic clamshells like the ones at Costco, I kept my distance, feeling that unless I was going to pick them myself, whatever herbs and lettuces I bought for salad should have the best possible defense system against the indignities of transport, refrigeration, and neglect.

You mention lining your Costco bin with paper towels in an attempt to forestall decay. This is a reasonable approach, though about fifty percent of the Internet suggests that the best place to put these prophylactic towels is on top. A small but vocal percentage of the Internet tries to split the difference by layering paper towels between every layer of lettuce—something I’ve done myself, with herbs, when they were for a high-ticket-price fundraiser. My favorite variation on this theme, well explored on the spirited terrain of reddit, is from someone called myhf, reprinted below.

The hitch, with all of these, is that much clamshell or plastic-bag packing of greens uses a technology called Modified Atmosphere Packaging, which replaces air with a tailored mixture of Nitrogen, Carbon Dioxide, and Oxygen, proven to inhibit microbe growth and slow oxidation. I can’t tell from my cursory sleuthing whether Costco Spring Mix containers use MAP. But I can say with certainty that whenever a well-meaning consumer opens a clamshell or bag that has used it, they are also inadvertently speeding the decay of whatever the clamshell or bag holds.

When we both lived in New York City, my brother—also a chef—and I talked about getting t-shirts made with slogans like: Only eat age-appropriate greens! and Let the baby greens grow! We didn’t—we never got the slogans punchy enough—but our argument even had an environmental slant: When you harvest greens young, fewer nutrients and less fiber and less edible mass end up being produced—by the same quantity of resources—than if you let them mature. You write that what ties you to the Costco boxed spring mix is your husband’s preference—implying that, if he were to give a few inches, the problem might resolve itself. I find myself drawn toward finding a strategy to that end.

The Costco spring mix contains Green Leaf, Red Leaf, Oak Leaf, and Butter lettuces, plus spinach, arugula, frisee, radicchio, mizuna, and kale. What about using that list as a recipe for your own house mix? The first four taste the same—certainly when picked as babies. The varieties that might qualify the mix for a preference are arugula, frisee, radicchio, mizuna, and kale. Of those, I would wager than you could pick two or three and add them to any leaf lettuce to produce an almost identically-flavored mixture. You might also want to note that radicchio is a beautiful magenta color—which distinguishes it—and that frisee curls and tickles the tongue in a pleasant way.

What this strategy offers is flexibility to decide how much salad mix you’re going to make and how you’ll deploy it. Based on the Costco recipe, you can choose one type of leaf lettuce—maybe Red Leaf or Oak Leaf, for their prettiness—and buy two heads. Cut and wash one to add to your house mix. Keep the other, wrapped in paper towel, then plastic or beeswax, to be cut and washed when your first batch of mix is finished. Buy two heads of radicchio and do the same thing. Etc. Store the mix you make in an airtight container with towels wherever you want, and your problem will evaporate, along with any threatening moisture.

Dear cook, I still haven’t given you what you asked for: a recipe that uses the Costco spring mix that is too wilted to eat. Now I will, as a way to bridge the old way and the new. It’s a recipe from my third book, The Everlasting Meal Cookbook, and it should deal handily with the spring mix that is too wilted to use as salad, but not yet weepy and inedible:

Greenest most delicious sauce base (5 min) 1/2 cup wilted salad, 1 c chopped crunchy watery vegetables, like celery, peeled cucumber, lettuce hearts, or a combination, 1 packed cup chopped herbs like basil, cilantro, dill, chervil, sorrel, arugula, 1 clove chopped garlic, 2 tbsp sherry vinegar, ⅓ c olive oil, 1 tsp salt plus to taste. Blend until very, very smooth and airy. Combine with a handful of spring onions, soaked in lemon juice with salt for 10 minutes, and enough olive oil to make a green, green dressing, or add a dollop to homemade or store bought mayonnaise or creme fraiche for a creamy sauce, or add grated cheese for pasta sauce.