Dill Pickle Soup

Bahan-bahan (4 porsi)

• 3 tablespoons salted butter
• 1 medium yellow onion (diced)
• 3 ribs celery (diced)
• 1 medium carrot (finely diced)
• 2 tablespoons all-purpose flour
• 4 cups chicken broth
• 3 medium Yukon gold potatoes (about 1 pound)
• 1 ¼ cups finely diced dill pickles (see notes*)
• ½ teaspoon dried dill
• 1 teaspoon cornstarch (optional)
• ⅔ cup sour cream (plus additional for garnish)
• 2 tablespoons fresh dill (for garnish, optional)