In a large stockpot over medium-high heat, combine the butter, olive oil, onion, garlic, and celery. Cook 8 to 10 minutes, or until the onions are transparent. Sprinkle flour over the mixture and stir well to make a dry roux. Gradually add the chicken broth and stir until slightly thickened. Stir in the potatoes, dill, tarragon, thyme, and paprika. Reduce heat to medium, cover, and simmer for 15 minutes.