In a large pot, combine the chicken broth, potatoes, carrots, and butter. Bring to a boil over medium-high heat and cook until the potatoes and carrots are tender. Add the diced pickles and allow the soup to continue to simmer over medium heat.

In a medium mixing bowl, stir together the flour, sour cream and water, to make a paste. Vigorously whisk the sour cream mixture into soup, a spoonful at a time. You may see small bits of flour clumps in the soup, but they will break down as the soup continues to cook.

Add the pickle juice, Old Bay, salt (taste the soup first to see if it needs any salt after the addition of the pickle juice), black pepper, and cayenne pepper. Simmer the soup for 5 more minutes, then remove from the heat and serve hot.