A Favorite Way to Preserve Zucchini

One of my favorite cookbooks is “My Calabria” by Rosetta Constantino with Janet Fletcher. A favorite cookbook is one I want to read, which draws me into the author’s world, tell stories that are relevant to the food it presents, and provides context for recipes. It’s one where I learn techniques or about ingredients or a different way to do something in the kitchen. It’s one to which I go back repeatedly. It’s one from which I use several recipes on a regular basis. “My Calabria” does all of that!

I particularly love the recipe for Zucchini Sott’olio (Zucchini preserved under oil). It’s low key… meaning no need to get the canner out. And it yields jars redolent of summer. Many people do not guess “zucchini” when you serve it to them because the texture is meaty and mushroom-like.

In good years, the zucchini plants in my garden survive the squash bugs’ onslaught and yields lots of fruit. I don’t have to go beg local farms to save me their oversized zucchini, I can let mine grow big. And when I say big, I mean the size of my forearm. Small zucchinis are too delicate for this process and will dissolve in the vinegar bath.

All you need are a few large fresh unblemished zucchinis, salt, vinegar, garlic, herbs and spices for flavoring, and good olive oil. How many zucchini? Depends on you. Once, salted, and somewhat dried, the zucchini loose a lot of moisture (i.e. weight). For me, 5 lbs (2.25 kg) of zucchini yield approximately a pint (500 ml) of sott’olio.

Still, a few words of caution here: this process is not endorsed by the USDA. So… don’t feel comfortable with that? Don’t make it! As for me, I know it’s a technique that has been used along the Mediterranean shores (Calabria, Sicily, Provence, Greece all have similar types of preserves) for centuries, if not millenniums. If carefully done, I believe it’s safe.

How/why does it work? In a nutshell, you remove water from the zucchini by salting them. Once the zucchini have lost moisture and are reasonably dry, they are acidified by being boiled in vinegar. That lowers their pH enough that bacteria can’t survive. Finally, you keep air and molds (and bacteria) out by submerging the food completely in olive oil AT ALL TIMES. It’s a lengthy process, but not a difficult one, and with lots on inactive time. I enjoy it enough to make a few jars every year (even if I have to beg my farmer friends for large zucchinis).

It’s delicious serve on crostinis or polenta cakes or as part of an antipasti platter; or as a relish with any grain: rice, barley, grits…

Rosetta Constantino’s recipe is here. Still, I highly HIGHLY recommend her book. Here’s how I do it:

Day One

• Only use fresh and unblemished large zucchinis. Cut off the ends, slice lengthwise, Spoon out the spongy inside which surround the seeds (and the seeds), discard or reserve for another use (such as cream-style soup). Slice the halves zucchini in slices about 3/16″ to 1/4 ” thick (4 – 6 mm). Don’t slice too thin or they will dissolve in the vinegar bath.
• Weigh your zucchini. Use 4 Tablespoons (70g) of salt for every 5 lbs (2.25 kg) of prepared zucchini.
• In a large non-reactive container, layer the zucchinis and the salt (I like to use a pottery crock, the same one I use to prepare sauerkraut). Toss, cover with a clean kitchen towel, and let rest 8-12 hours, or overnight.

Day 2

• Drain the zucchini in a non-reactive colander. Take handfuls, and press with hard your hands to remove liquid. Put the squeezed zucchini in a large non reactive pans. Add 3 cups (750 ml) of vinegar mixed with 1 cup (250 ml) water (I use white vinegar, but Rosetta calls for white wine vinegar). Gently press on the zucchini to ensure they are mostly under vinegar. Gently bring to boil, stirring occasionally so that the slices at the top also get well immersed in vinegar. Boil gently for 5 minutes, but watch. You want the slices to remain whole.
• Drain in a non-reactive colander with a weight (such as a large bowl or pot filled with water) to help squeeze liquid out of the zucchinis. Let rest for 1 hr or so with the weight on top.
• Put several layers of clean kitchen towels on top of wooden boards and spread the zucchini slices, not overlapping.

Day 2-4

• Let the zucchini dry out at room temperature. Once a day turn them and change the top towel which will have absorbed some moisture. Do this until the zucchinis have considerably shriveled, and no longer feel damp, 24-48 hrs depending on the ambient conditions. (alternatively you could use a dehydrator on low for an hour or two)
• Meanwhile thinly slice 5 cloves of fresh plump garlic (for 5 lbs of zucchini) and cover them with vinegar.

Day 3 (or 4)

• In a large bowl, toss the zucchini slices, the drained garlic slivers, Cayenne or crushed hot pepper flakes and herbs/spices together with just a little extra virgin olive oil. Let rest, covered for up to 4 hours. Rosetta uses mint which is delightful. Other herbs/spices possibilities are:
  • nepitella
  • cumin, coriander & oregano
  • fresh ginger and turmeric, thinly sliced or minced (and soaked in vinegar first for a few hours)
  • rosemary & sumac
• While the mix is resting, sterilize a few pint jars (5 lbs of prepared zucchinis will fill 1-2 pint jars depending how much drying occurred)
• Put a little bit of olive oil at the bottom of the jar and fill them with zucchini slices, packing well by pressing with a spoon or fork to remove any air gap. As you go add a little olive oil and keep pressing the slices to 1 inch from the top of the jar (2.5 cm). Then pour 1/4″-1/2″ inch of oil (1-1.25 cm) on top to ensure all the slices are completely covered in oil. Seal, label and date, and refrigerate (or put in a cold cellar).
• Let rest at least 2 weeks before using to allow the flavors to meld. Remove from the fridge an hour or two before you plan to use so the oil liquefies to room temperature. When you are done, pack down the remaining slices, add more olive oil if needed to completely cover them and refrigerate.

The jars should remain good – if refrigerated with the zucchini well packed and completely submerged in oil – for 6 to 9 months. Any left-over olive oil from the jars can be used for salad dressing or cooking.