Add chicken broth, potatoes, pickles, pickle juice, onion, and garlic to the slow cooker.
Cook on low for 6-8 hours or high for 3-4 hours until potatoes are tender.
In a small bowl, whisk sour cream and flour together. Add a few tablespoons of soup broth to temper, then stir back into the soup.
Cook for an additional 15 minutes to thicken the soup.
Season with black pepper and salt to taste before serving.