LEMONY SPINACH SOUP WITH FARRO

Steps:

• Melt the butter or heat the olive oil in the bottom of a large, heavy-bottomed pot over medium-high heat. Stir in the leeks and celery. Cook, stirring occasionally, until vegetables are tender, about 10 minutes. Stir in the garlic, rosemary and bay leaves; cook 1 minute more. Stir in the potatoes, stock, 2 cups water, 1 1/2 teaspoon salt and 1/2 teaspoon pepper. Bring to a boil; reduce heat to medium and simmer, partly covered, until vegetables are tender, 30 to 40 minutes.
• Meanwhile, bring a medium pot of salted water to a boil. Add farro and cook according to the timing on the package until just tender, about 20 to 30 minutes. Drain.
• Discard rosemary branches and bay leaves from the soup pot. Add spinach, cilantro and parsley, and simmer uncovered until very soft, 5 to 8 minutes. Using an immersion blender, purée soup until smooth. (Alternatively, you can purée the soup in batches in a blender or food processor.) If the soup is too thick, add a little water. If it's too thin, let it simmer uncovered for another few minutes to thicken. Stir in lemon juice and more salt to taste. Stir in farro.
• To serve, ladle the soup into bowls and top with a drizzle of olive oil, a few drops of lemon juice, flaky salt, red-pepper flakes and a little grated cheese, if desired.