Step 1

Heat 2 tablespoons butter in a pot over medium heat; cook and stir onion and dill pickle until onion is translucent and soft, 5 to 10 minutes. Add water and bring to a boil for about 30 seconds.

Step 2

Transfer pickle mixture to a blender; add dill pickle juice and dill. Blend mixture until smooth; add half-and-half and blend until smooth. Pour soup back into the pot.

Step 3

Stir celery salt into soup and bring to a simmer.

Step 4

Combine 1 tablespoon butter and flour together in a skillet over medium heat; cook and stir until roux is smooth and lightly browned, about 5 minutes. Stir roux into soup until thickened.