Recipe: Fermented Horseradish for Passover

Spring has always symbolized a time of renewal, change, and freedom. It is a time of rebirth and new beginnings. Celebrations of spring are joyful and full of color. Traditional springtime feasts feature fresh young vegetables, tender meats, and the first fruits of the season. Spring, in other words, is sweet.

Yet, one of my favorite spring dishes is none of the above. It is bitter, sharp and a plain off-white color. I'm speaking, of course, of horseradish, or chrein.

My appreciation for horseradish starts with its traditional use in the Passover seder. Passover, which commemorates the deliverance of the Jewish people from Egyptian slavery, features many traditional symbols of spring, and celebrates both the rebirth of nature and spiritual renewal. It is festival of liberation.

After matzoh, the most famous element of the Passover seder is maror, or bitter herbs. These bitter herbs are meant to be a reminder of bondage, that even in a celebration of freedom, it is important to remember the suffering of the past; to experience, symbolically, the bitterness of slavery. It is admonition, through taste, to think on the continued suffering of the oppressed and reflect on our own privileged emancipation.

This is important, I believe, no matter what your system of belief is. Every spring feast should have at least one bite, a kayazit perhaps (about the size of an olive), of bitter herbs.

In any case, while horseradish may seem ideally suited for this purpose, it would not have been part of the earliest seders, since it is not native to the Middle East. The historic reference (from the Mishnah) most commonly associated with horseradish as a bitter herb is tamcha. Unfortunately, the true identity of tamcha is not known with any certainty, but it is believed to be a reference to a type of wild parsnip, sometimes called gingidion, commonly grown in Syria in ancient days. Horseradish became popular as maror as the diaspora moved into more northerly climates, where leafy vegetables and lettuces were less common, but horseradish was readily available.

While rabbis may debate the appropriateness of horseradish as maror, its popularity as a traditional part of the seder is undeniable. This is in no small part because of its flavorful "bitterness." And how else are you going to eat your gefilte fish?

In actuality, horseradish is not so much bitter as it is sharp, thanks to a chemical reaction that takes place when the plant is cut or grated. This protective enzymatic reaction is meant to defend the plant from herbivores and creates the pungent chemical, allyl isothiocyanate, otherwise known as mustard oil.

Traditionally, horseradish is grated then vinegar is added to preserve the pungency. And this is a fine thing. Rather than vinegar, however, why not try lacto-fermentation instead? You gain all the nutritive and probiotic benefits of fermentation, as well as a mellower, more complex flavor that makes this a popular condiment with all sorts of dishes -- not just on matzoh.

WARNING: Imagine the strongest onion you've ever cut that brought tears to your eyes. Multiply that by 10. Grating horseradish calls for a well-ventilated space and an ability to hold your breath. If you've ever been sprayed by mace or tear-gassed, the sensations you feel when grating horseradish will seem familiar.

Lacto-fermented Horseradish

For the ferment
8 oz Horseradish, peeled and freshly grated (a food processor is recommended for all but masochists)
4 oz Parsnip, peeled and freshly grated
¼ oz Salt (no additives: if the ingredient list is "salt" only, you're good to go)

For the brine
2 Cups Water (unchlorinated)
¼ oz Salt (again, no additives)

Procedure:

1. Toss the grated horseradish, parsnip and salt until thoroughly mixed.
2. Transfer this mixture to your fermentation vessel, such as a glass jar. An airlock fermentation kit is recommended. Pack firmly in your clean fermentation jar until the salt is drawing liquid from the vegetables.
3. Add the brine to your fermentation jar until the horseradish mixture is completely submerged. You may not need all the brine.
4. Place a clean weight (stone, glass, ziplock bag filled with brine) in your jar to keep the horseradish mixture submerged.
5. Cover your jar with cloth, or a lid that hasn't been completely sealed (to allow the escape of fermentation gasses). Again, an airlock is recommend.
6. Store out of direct sunlight at room temperature for a minimum of three days and up to two weeks while fermentation takes place. The longer the fermentation, the more mellow the horseradish (to a certain point) and the more sour and tart the fermentation flavors.
7. Refrigerate and enjoy! Fermented horseradish should last several months in the refrigerator.

Caution: If your horseradish becomes soft, slimy, grows mold, or develops a disagreeable odor, discard.

Notes:

This recipe incorporates parsnip with the horseradish. This is for several reasons: first, one of the traditional bitter herbs in ancient days was a relative of the parsnip; second, grated parsnip and horseradish are virtually indistinguishable visually; and, third, parsnip mellows out the horseradish and provides a gentle sweetness for a more round flavor. You can vary the ratio of parsnip to horseradish to suit your tastes.

One very popular alternative is to substitute beets for the parsnip for a more traditional red colored horseradish condiment. The recipe is exactly the same -- just substitute peeled, grated red beets for the parsnip. As with the parsnip, you can vary the ratio (more or less beet to horseradish) to achieve a combination you find pleasing.

Hot Enough For You?

Fermented horseradish retains some of its mustard pungency, but nothing like freshly grated or some of the store bought "prepared" horseradish condiments. Sometimes, you still want that sinus-clearing effect of freshly grated horseradish. The secret is adding a few drops (emphasis on "few") of mustard oil (essentially 95% pure allyl isothiocyanate in oil) before use.

However, not any mustard oil will do. Most mustard oils found in stores are for external use only, frequently recommended as massage oils or to stimulate hair growth. The USDA does not allow them to be sold as a food product because they contain potentially unsafe levels of erucic acid.

You can find edible mustard oil in some Japanese grocery stores, where it is known as "vegetable oil with horse radish" or "wasabi oil." A few drops of this mixed into your fermented horseradish, mustard, or any dish, will give it that allyl isothiocyanate kick.