When my family settled in Vancouver in the early 1980s, what we lacked in furnishings we more than made up for with a freezer packed with party-size plastic tubs of ice cream and an overflowing fridge of gallon jugs of milk.

At first glance you might mistake us for a milk-drinking obsessed family, which couldn’t be further from the truth. What we were passionate about, however, was the magical transformation of the milk into two equally magical products. One that soothed our homesick hearts: yogurt. And another that indulged our taste buds; sustained us economically in our newly adopted home; and ultimately filled those ice-cream tubs (once the contents were happily consumed, in large part thanks to me): kashk.

Like so many immigrants before her, my mother, a university professor and poet by trade, turned to food to provide for the family. She set out to supply the lone Iranian market in the city at the time with various Iranian goods, including homemade kashk, packed and delivered in repurposed ice cream buckets. As we got closer to Nowruz, Iranian New Year, she also made sure to set aside a bowl of kashk for our pot of aash-e reshteh — the hearty, herb-based, bean and noodle soup served around the new year celebrations.

Iranian kashk is a rich, creamy, sour, sometimes salty, nutritious and deeply flavorful dairy product. Think of it as a more assertive and soulful cousin of thick yogurt or sour cream. Its fermented acidic notes appeal to the sour-leaning Iranian palate, and add depth and body to an assortment of dishes. Kashk, in varying preparations and names, is also used in several neighboring countries and regions, such as Afghanistan, the Caucasus, Iraq, Lebanon, Turkey and Palestine.

To understand Iranian kashk is to appreciate the centuries-old art of preservation in Iranian cuisine.

Before the days of refrigeration, and even today, shepherds throughout Iran have had to efficiently make use of the abundance of the fresh milk they produce. In an effort to keep the milk from spoiling, it is put through a series of transformations and fermentations.

The cycle that eventually leads to kashk begins with the milk being cooked, cultured and transformed into yogurt. The yogurt is then churned. In this process, the fat separates and turns into butter, and the liquid that is left over is called doogh.

Iranian kashk is traditionally made with the doogh left over from making yogurt butter. These days, the word doogh is commonly associated with the popular mixed drink of yogurt, water, salt and mint. In English, the words buttermilk or whey are used to define this liquid. (The buttermilk that is available in our grocery stores is the liquid left over from churning cream into butter, and is not used for making kashk.)

Doogh is naturally fat-free, since the fat has separated, and boasts plenty of nutrients, such as calcium and protein. There are varying preparations of kashk. Traditionally, in Iranian villages, the doogh is placed in large sacks and set out to strain for a long period of time. More typically, the doogh is cooked with some salt until it splits and curds rise to the top. It is then strained in a sack, and the creamy ingredient left over in the sack is called kashk.

To preserve kashk, it is left to strain and pressed to remove all the moisture. It is then formed into round or oval balls and left out to completely dry and ferment. The dried balls are then reconstituted with water, turned into a creamy liquid and used.

To complete the cycle, the liquid remaining from straining kashk is further cooked, reduced, thickened with wheat starch, and turned into a very tangy and potent paste called ghara ghoroot (black kashk). Not a single drop of milk wasted.

These days, with the availability of refrigeration, it is more convenient to use jarred liquid kashk, rather than reconstituting dried kashk. Preparing homemade Iranian liquid kashk is quite simple; it just takes time and a little patience — something we’ve all had to have more of this past year.

Natural doogh is not easily attainable outside of Iran, but you can still produce an incredibly tasty liquid kashk at home by combining soured yogurt, water and salt to taste. This mixture is cooked similarly to the doogh preparation and then strained in a sack or cheesecloth for a couple of minutes. The kashk is then blended with a little water, if necessary, for a smooth and creamy consistency and stored in a jar in the fridge or freezer. Homemade kashk is much closer in taste and texture to that of kashk prepared the traditional way with doogh in Iran.

If making homemade kashk is not an option, store-bought jarred liquid kashk, often labeled as whey, is readily available at Iranian markets and online. Keep in mind, store-bought kashk is saltier than homemade.

Kashk can be stirred in as a final ingredient, or dolloped on as a garnish, to enrich and add tang, creaminess and depth of flavor to a variety of dishes (such as soups, dips or roasted vegetables). Use it just as you would yogurt or sour cream. If your jarred kashk is too thick, you can thin it out with water. Like yogurt, kashk can also split when heated and shouldn’t be boiled or cooked too long.

Aash-e reshteh gets its final kick of flavor from kashk. As does the beloved Iranian eggplant dish — kashk-o bademjan (pictured above) — which means kashk and eggplant. Despite its humble name, kashk-o bademjan bursts with complex flavors. Although not traditional, it has found a permanent place at my Nowruz table. I like to serve kashk-o bademjan as an appetizer before we settle in for our Nowruz meal of sabzi polo, mahi and kookoo sabzi.

This Nowruz, I won’t be filling ice cream buckets with kashk. But, like my mother almost 40 years ago, I will stand sentinel and determined next to the pot of yogurt simmering away on the stove, and try my best to navigate a new world facing unforeseen challenges. Then I’ll fill a jar with fresh kashk — just enough to stir into our aash-e reshteh and kashk-o bademjan, and welcome a new year — with hopes for brighter days ahead.

Chef Hanif Sadr of Komaaj in San Francisco contributed to this story.

Naz Deravian’s cookbook “Bottom of the Pot” was featured in our Voraciously’s Essential Cookbooks newsletter series in which Charlotte Druckman’s curated list of 10 cookbooks she believes are essential to a modern home cook’s repertoire. Sign up for the 10-week series here.

Liquid Kashk With Yogurt

Traditionally in Iran, the yogurt for making kashk is left at room temperature for 2 days to sour. Another method is to decant the yogurt into a bowl, place a stainless steel spoon in it, and leave it at room temperature for 2 hours. You can use refrigerated yogurt, but the kashk might not get as tangy.

To properly strain the kashk, you will need a mesh strainer and a nut milk bag or several layers of cheesecloth. A nut milk bag made of nylon or similar heavier fabric is preferable. To measure the water, simply fill the empty yogurt container with water.

Storage Notes: Kashk can be refrigerated in an airtight container for up to 1 week or frozen for up to 3 months.


Ingredients

  • 1 (32-ounce) container plain sour yogurt
  • 4 cups cold water
  • 1 tablespoon kosher salt

Step 1

In the pitcher of a blender, combine the yogurt, water and salt and blend until smooth and the salt dissolves, about 1 minute.


Step 2

Transfer the mixture to a medium pot set over high heat and bring to a boil, stirring constantly so the mixture doesn’t overflow. Reduce the heat to medium-low and simmer for 2 hours to 2 hours 30 minutes, stirring occasionally and making sure nothing sticks to the bottom of the pot. The yogurt will separate, break down and develop a distinct tart smell, and you will start to see curdled pieces of yogurt rise to the top — that’s what you want.

Eventually, most of the water will evaporate, leaving a thick batch of curds in the pot. The color can range from a creamy white to a pale beige. Remove the pot from the heat and cool for 5 minutes.


Step 3

Place a fine-mesh strainer over a large bowl. Prepare a nut milk bag or several layers of tightly woven cheesecloth and line the sieve with it. Very carefully, ladle out the contents of the pot (the liquid and the curds) into the nut milk bag or cheesecloth. Let strain for 1 minute; what is left in the bag or cheesecloth is kashk. Save the liquid to thin out the kashk, if necessary.


Step 4

Return the kashk to the blender and process until smooth. If necessary to achieve the desired consistency, drizzle in the saved liquid, a few drops at a time (you can use fresh cold water if you prefer). Taste, and season with more salt, if needed. The kashk should have the consistency of strained yogurt. Transfer the kashk to a small container until cool to the touch, cover and refrigerate until needed.


Nutrition Information

Ingredients too variable for meaningful analysis.


Adapted from cookbook author Naz Deravian.

Tested by Ann Maloney and Jim Webster; email questions to voraciously@washpost.com.

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A few recipes that could be enhanced with kashk from Voraciously: