White Borscht Soup

1.In a large pot over medium heat, melt the butter. Add the onion, leeks, carrots, celery, salt and pepper and cook until soft and translucent, 10 to 12 minutes. Add the garlic and cook for 1 to 2 minutes until softened and fragrant. Add the potatoes, broth, bay leaf and whole kielbasa.
2.Bring to a boil and reduce to a simmer for 15 minutes until the potatoes are tender. Remove the bay leaf (you can discard) and the kielbasa. Thinly slice the kielbasa, crosswise, into coins and set aside. Add the bread and pickle brine and stir to combine.
3.Blend the soup using an immersion blender. Adjust the seasoning with salt and pepper. Return the sliced kielbasa into the pot. Ladle into bowls and serve with a dollop of sour cream, some chopped dill pickles, fresh parsley and bread for dunking.