Aush-e-reshteh (Herb and Noodle Soup)

• 1 lamb shank, 1 1/2 to 2 pounds
• Salt and freshly ground black pepper
• 2 tablespoons olive oil
• 2 onions, thinly sliced
• 2 cloves garlic, finely chopped
• 1/2 teaspoon ground turmeric
• 1/4 cup dried kidney beans, washed and soaked in cold water at least 2 hours, drained
• 1/4 cup dried navy beans, washed and soaked in cold water at least 2 hours, drained
• 1/4 cup dried chickpeas, washed and soaked in cold water at least 2 hours, drained
• 1/4 cup lentils
• 2 1/2 cups beef broth
• 1/4 pound reshteh (Persian noodles) or linguine, broken in half
• 1 1/2 teaspoons all-purpose flour
• 1/2 cup coarsely chopped scallions
• 1/2 cup coarsely chopped fresh dill
• 1 cup coarsely chopped fresh parsley
• 2 pounds fresh spinach, stems removed, rinsed well, and coarsely chopped
• 1/2 cup kashk (Persian whey) or sour cream, plus a dollop for garnish

Season the lamb shank generously with salt and pepper. Heat the olive oil in a large, nonreactive, heavy-bottomed soup pot. Add the lamb and brown on all sides. Add the onions and garlic and sauté over medium heat until translucent. Season with additional salt, pepper, and the turmeric. Add the drained kidney beans, navy beans, and chickpeas, and sauté for an additional 3 or 4 minutes. Add 7 cups of water. Bring to a boil, skim the froth that rises to the top, cover, and simmer for 45 minutes over medium heat. After 45 minutes, add the lentils and beef broth. Cover and simmer for an additional 50 minutes. You can stop here and refrigerate the soup overnight. As with most soups, it will improve after sitting for a day. Reheat the soup before adding the noodles and flour. Cook for 10 minutes, stirring occasionally.

Add the chopped scallions, dill, parsley, and spinach, and continue cooking for 30 minutes more, or until all of the beans are tender. Remove the lamb shank. You can pick the meat off the bones and stir it into the soup if you desire. Check the seasoning and add more salt and pepper if needed. More water may be added at this point if the aush is too thick. Stir in whey (or sour cream) and mix well.