Heat butter and oil in a Dutch oven over medium heat until the butter melts. Add the leek, potato, and celery. Cook, stirring occasionally for about 4 to 6 minutes. Add the chopped dill and stir. Add the peas, water and broth bringing it to a boil, then lower the heat to a simmer for about 15 minutes. Using an inverted blender, pulse the soup so its chunky, not a total puree. If you don’t have an inverted the soup, cool for 30minutes then carefully pulse in a blender to just chunky. Serve in bowls and garnish with dill springs.