Iranian Curd Soup: A Hearty Persian Ash-e Kashk Recipe

Iranian curd soup, often called ash-e kashk, is a thick Persian soup of lentils, beans, fresh herbs, noodles, and tangy kashk, a cultured whey product. The balance of creamy legumes, fragrant greens, and sharp curd makes it a satisfying meal, and family and regional versions vary in their beans, herbs, and use of noodles.

Ingredients

4 tablespoons (60 ml) neutral oil or olive oil, divided
2 large yellow onions (about 400 g), thinly sliced; use one for the soup base and one for the garnish
4 garlic cloves (about 20 g), minced, divided
1 teaspoon ground turmeric (3 g)
½ teaspoon ground black pepper (1 g)
1 cup (190 g) brown or green lentils, rinsed and picked over
8 cups (1.9 L) water or low-sodium vegetable broth, plus up to 1 cup (240 ml) hot water to loosen the soup if needed
1 teaspoon fine salt (6 g), then more to taste
1 can chickpeas, 15 ounces (425 g) before draining; drain and rinse, about 1½ cups (240 g) drained
1 can cannellini or other white beans, 15 ounces (425 g) before draining; drain and rinse, about 1½ cups (240 g) drained
2 cups chopped parsley (about 60 g)
1 cup chopped cilantro (about 30 g)
1 cup chopped fresh dill (about 25 g)
4 packed cups chopped spinach (about 120 g)
1 cup chopped scallions (about 100 g)
3 ounces Persian reshteh noodles (85 g), broken into shorter lengths; linguine broken into pieces is a practical substitute
1 cup liquid kashk (240 ml), plus 2 tablespoons (30 ml) for serving if desired
2 teaspoons dried mint (about 2 g)

Instructions

Prepare the vegetables. Rinse the lentils under cool water and remove any small stones or damaged lentils. Slice the onions, mince the garlic, and chop the herbs, spinach, and scallions. Keep one sliced onion and about half of the garlic aside for the topping. If the kashk is very thick, whisk it with a few tablespoons of water until pourable; its saltiness varies, so wait to adjust the soup’s seasoning until near the end.
Cook the onion base. Heat 1 tablespoon (15 ml) of the oil in a large, heavy soup pot over medium heat. Add one sliced onion and cook for about 10 minutes, stirring often, until soft and golden at the edges. Stir in half the garlic, the turmeric, and black pepper; cook for 1 minute, just until fragrant. Keep the garlic moving so it does not scorch, which would make the soup taste bitter.
Simmer the lentils. Add the rinsed lentils, water or broth, and salt to the pot. Bring the liquid to a boil, then lower the heat to maintain a steady simmer. Partially cover and cook for 25 minutes, stirring once or twice. The lentils should be tender but still hold their shape. If the pot boils vigorously, lower the heat; rapid boiling can break the lentils down before the herbs have cooked.
Add the beans and greens. Stir in the drained chickpeas and white beans, parsley, cilantro, dill, spinach, and scallions. Simmer uncovered for 20 minutes, stirring from the bottom every few minutes as the greens soften and the soup thickens. While this simmers, make the onion-and-mint topping in a separate skillet. If the soup is already very thick, add some of the reserved hot water; the noodles will absorb more liquid later.
Make the garnish. Heat 2 tablespoons (30 ml) of the remaining oil in the skillet over medium heat. Add the reserved onion and cook for 10 to 12 minutes, stirring regularly, until golden brown and soft. Add the remaining garlic for the final minute. Transfer about half of this onion mixture to a small bowl. Add the last tablespoon (15 ml) of oil and the dried mint to the skillet, stir for 20 to 30 seconds, then remove it from the heat. Dried mint can turn bitter if fried for too long, so keep this step brief.
Cook the noodles. Break the reshteh into roughly 2-inch (5 cm) pieces if it is long, then stir it into the soup. Simmer for 8 to 10 minutes, or follow the package timing if using another noodle. Stir frequently near the end because the noodles can settle and stick to the pot. They should be tender, not mushy; the soup will continue to thicken as it stands.
Finish with kashk. Turn the heat to low and stir in 1 cup (240 ml) kashk. Warm the soup gently for about 4 minutes, stirring, without letting it boil hard. Taste and add more salt only if needed. If it has become thicker than you like, stir in a little hot water. Serve each bowl topped with the reserved golden onions, mint oil, and a small drizzle of extra kashk.

Tips

Check the kashk label before salting. Kashk is a tangy, salty whey curd sold in liquid or dried form in some Middle Eastern markets. Liquid kashk is easiest here. If you have dried kashk, reconstitute it according to its package directions and measure 1 cup (240 ml) after mixing; brands differ in concentration. Add the soup’s salt gradually because both kashk and broth can contribute plenty.
Use an appropriate substitute if needed. Plain, unsweetened whole-milk yogurt can stand in for kashk, but it is usually milder and less salty, so the soup will taste less sharply tangy. Take the pot off the heat, whisk the yogurt with a ladleful of hot broth, then stir it in; do not boil the soup afterward, as yogurt can split. Thick plain yogurt gives a closer body than thin yogurt.
Mind the thickness. Ash-e kashk is meant to be substantial, but noodle brands and simmering pots vary in how much liquid they absorb. Keep hot water nearby and add it a little at a time if the soup becomes pasty. If it looks loose at first, give it a few minutes off the heat before adding more noodles or beans; lentils and noodles keep absorbing liquid as they rest.
Chop the greens fairly evenly. Finely chopped herbs distribute through the soup and make it easier to serve, while very large pieces can tangle with the noodles. Wash herbs well and dry them before chopping. If using frozen spinach instead of fresh, thaw it and squeeze out excess water so it does not dilute the broth.

Serving Suggestions

Serve ash-e kashk hot in wide bowls, with the crisp-edged onion, mint oil, and a little extra kashk arranged on top rather than stirred in. The garnish is more than decoration: its sweet onion, fragrant mint, and tart curd contrast with the mellow lentils and greens. Offer lemon wedges for anyone who wants a brighter, more acidic finish, and put extra chopped herbs or kashk on the table so diners can adjust their bowls.

For a full meal, pair the soup with warm flatbread such as lavash or sangak, or with a simple plate of radishes, cucumber, and fresh herbs. A small side of pickled vegetables also works well against the soup’s creamy texture. Because the beans, lentils, and noodles make it filling, modest sides are usually enough. If serving it as part of a larger meal, offer smaller bowls and keep the soup warm over very low heat, stirring occasionally.

Variations

There is no single fixed formula for ash-e kashk. Some cooks use a larger share of fresh herbs, while others add less dill or leave it out. You can replace some or all of the spinach with chopped beet greens, chard, or additional parsley. These greens change the color and flavor slightly; tougher leaves should be chopped small and given enough time to soften. If using a mix, keep the total amount close to the recipe’s roughly 9 cups (about 335 g) of prepared greens so the soup remains balanced.

For a version without noodles, leave out the reshteh and add 1 to 2 cups (240 to 480 ml) extra broth if you prefer a looser soup. The result is less starchy but still hearty from the lentils and beans. You can also replace either canned bean with another cooked white bean, such as navy beans. Canned beans are convenient and consistent; if starting with dried chickpeas or beans, cook them separately until tender before adding them, rather than relying on the soup’s simmer to soften them in time.

Reshteh are Persian noodles traditionally used in some versions of the soup. When they are hard to find, broken linguine or another plain wheat noodle works; it will not have exactly the same texture, but it cooks in the same pot and is easy to source. For a vegan bowl, use vegetable broth and check that the noodle contains no egg, then replace kashk with a suitable unsweetened plant-based yogurt. That swap changes the characteristic whey tang, so add a little at a time and taste before serving.

Storage and Reheating

Cool leftovers promptly and refrigerate them within 2 hours of cooking in a covered container. The soup keeps for 3 to 4 days in the refrigerator. It will thicken considerably as the noodles and lentils absorb broth, so store a little extra broth or water separately if you want to restore a looser consistency. If you expect leftovers, you can also cook the noodles separately and add them to each serving; this helps them keep a firmer texture.

Reheat only the portion you need in a saucepan over medium-low heat, stirring often and adding a splash of water or broth until it loosens. Heat until steaming throughout, and bring leftovers to 165°F (74°C) for safe reheating. Avoid a hard boil after kashk or yogurt has been added, which can make the dairy separate; gentle heat and frequent stirring help keep the soup smooth. Freeze portions for up to 2 months for best quality, preferably before adding the kashk and noodles. Thaw overnight in the refrigerator, reheat gently, then add freshly cooked noodles and kashk.

Frequently Asked Questions

What is kashk, and where can I find it?

Kashk is a cultured, fermented whey product used in Iranian cooking for its distinctive salty, tangy flavor. It may be sold as a thick liquid or as dried pieces or powder in Persian and other Middle Eastern grocery stores. Check the package for dilution instructions if it is dried, and taste before adding extra salt. If you cannot find it, plain whole-milk yogurt is a workable but milder substitute; temper it with hot broth and keep the soup below a boil after adding it.

Is ash-e kashk the same as ash reshteh?

They are related Iranian herb-and-legume soups, and recipes can overlap, but the names are not always used for exactly the same version. Ash reshteh is particularly associated with reshteh noodles, while ash-e kashk highlights kashk as a defining ingredient and may be made with or without noodles depending on the cook. This recipe includes both noodles and kashk, a combination that makes a thick, meal-like bowl.

Can I make this soup with dried chickpeas and beans?

Yes, but cook the chickpeas and beans separately before adding them. Dried legumes take longer to soften than the lentils in this recipe, and acidic or salty ingredients can slow that process. Once cooked until tender, use roughly 1½ cups (240 g) of each, matching the drained amount from the cans. Do not add the dried beans directly to the soup and assume they will be ready during the stated cooking time.

Why did my soup become so thick?

Lentils, noodles, and chopped greens all absorb liquid, especially as the soup cools or sits overnight. Stir in hot water or broth a little at a time while reheating until it reaches the consistency you want. If you have not added the noodles yet, you can also hold some back and cook them separately. Season again after thinning, since extra liquid can soften the salty and tangy flavors.

Can I prepare ash-e kashk ahead?

Yes. The lentil, bean, and greens base can be cooked a day ahead, cooled promptly, and refrigerated. For the best noodle texture, cook the reshteh shortly before serving, then warm the base and finish with kashk. The onion and mint topping can also be made ahead and refrigerated separately; warm it gently before spooning it over the bowls. Follow the storage limits above, and do not leave the cooked soup at room temperature for more than 2 hours.

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