This soup is served during the festivities leading up to Nowruz, the Persian New Year. Two uniquely Persian ingredients define its flavour: Reshteh, or flat noodles, are starchier and saltier than their Italian counterparts, and as they cook, the starch thickens the soup. Kashk, a form of dried, drained yoghurt or whey, is saltier and more sour than Greek yoghurt or sour cream. The feta-like kashk gives ash its distinct flavour. Look for both items at a Middle Eastern grocer.
¼ cup dried chickpeas
¼ cup dried white beans, such as haricot or cannellini
fine sea salt and freshly ground black pepper
450g coriander (about 3 large bunches)
450g Italian parsley (about 3 large bunches)
2 large bunches dill
1 large bunch chives
about 20 large fresh mint leaves
4.5 tbsp plus ⅓ cup extra-virgin olive oil
2 large yellow onions, 1 finely chopped and 1 thinly sliced
2 garlic cloves, minced
1 cup dried green or brown lentils
½ tsp ground turmeric
2 litres chicken or beef stock (preferably homemade; use vegetable stock if vegetarian), or water
1½ cups liquid kashk (Persian sun-dried yoghurt or whey), plus ½ cup, for serving
225g reshteh (Persian soup noodles)
3 tsp dried mint
1. The night before you plan to cook, place chickpeas and white beans in a medium bowl. Add a generous pinch of salt and two cups of water. Refrigerate overnight.
2. The night before or just before cooking, prepare the herbs and greens: Wash spinach, coriander and parsley, then use a salad spinner to dry very well. Run a knife through the spinach to cut leaves into large pieces. Trim the woody ends from coriander, parsley and dill so that only leaves and tender stems remain. Roughly chop coriander, parsley, dill, chives and mint leaves into pieces no larger than a 10-cent piece. If preparing ahead of time, wrap chopped greens and herbs in plastic bags and refrigerate overnight.
3. To cook, set a large (at least 10-litre) Dutch oven or stockpot over medium heat and add three tablespoons oil. When the oil shimmers, add the chopped onion and a generous pinch of salt. Cook, stirring regularly, until the onion is tender and golden brown, 16 to 18 minutes. Add garlic and cook, stirring constantly, for one minute.
4. Drain the beans and add to onion along with the lentils, turmeric and one teaspoon pepper. Cook for two minutes, stirring to coat the beans with oil and spices. Add the chopped spinach and herbs, along with stock or water, and stir to combine. Partly cover the pot with a lid and bring to a boil, then reduce the heat to simmer the soup for one hour, stirring regularly to prevent the greens from sticking and burning. If the soup remains very thick even after the greens have wilted, add another one to two cups water, as needed to thin it.
5. Place one-and-a-half cups kashk in a medium bowl. Add a ladle or two of hot soup and whisk to dissolve, then add the mixture to the pot. The kashk will change the colour of the soup from bright to milky green. Increase the heat and bring the soup to a boil, then break the noodles in half and add to the pot. Stir gently to mix in the noodles and keep them from sticking together, then reduce heat and simmer, stirring occasionally, until noodles are soft and chewy and the beans are completely tender, about 30 minutes.
6. In the meantime, prepare the garnishes: Set a medium frying pan over medium-high heat. When the pan is hot, add one-and-a-half tablespoons oil. When the oil shimmers, add sliced onion and a generous pinch of salt. Cook, stirring regularly, until golden brown and caramelised, 16 to 18 minutes. Spread cooked onion onto a paper towel-lined plate to absorb excess oil; let cool. Wipe out pan and return to medium heat. Add remaining one-third cup oil and warm gently over low heat, then stir in dried mint and remove from heat. Set mint oil aside and allow to steep for at least five minutes.
7. Place remaining half-cup kashk in a small bowl and thin out with a couple of tablespoons of water until it's the texture of thin yoghurt. Set aside.
8. The soup should be as thick as a hearty chilli con carne. If it's any thicker, thin it with water, half a cup at a time. Taste and adjust the seasoning with salt as needed, accounting for the fact that both the noodles and the kashk are well salted.
9. To serve, ladle soup into individual bowls. Drizzle with reserved kashk and mint oil, then top with a sprinkling of golden onions.
This is one of Samin Nosrat's 10 essential Persian recipes.
Samin Nosrat is the author of Salt, Fat, Acid, Heat and star of the related Netflix show. This recipe originally appeared in The New York Times.