- 1 tablespoon butter
- 3 leeks (white and pale green parts only), thinly sliced
- 5 pounds potato, peeled and thinly sliced
- 2 quarts chicken broth
- 3 cups frozen peas
- 1 pinch dried tarragon
- 3 cups milk
- salt and ground black pepper to taste
- Melt butter in a large pot over medium-high heat. Cook and stir leeks in the melted butter until tender, 5 to 7 minutes.
- Stir potatoes and chicken broth into the leeks and bring to a boil; reduce heat to medium-low, cover the pot, and simmer until potatoes are tender, about 12 minutes.
- Stir peas and tarragon into the soup; simmer until peas are tender, about 5 minutes.
- Pour the soup into a blender, filling the pitcher no more than half full.
- Hold down the lid of the blender with a towel and carefully start the blender, using a few quick pulses to get the soup moving before leaving it on to puree. Puree in batches until smooth and pour into a clean pot. Alternately, you can use a stick blender and puree the soup in the pot.
- Pour milk into the pureed soup and bring to a simmer over medium heat until heated through. Season with salt and black pepper.