Heat oil in a large dutch oven over medium heat. Add mushrooms to pan; cook 5 mins, stirring frequently. Add onion; cook 6 minutes. Add celeriac, parsnip and carrot; cook 4 minutes or until the onion is tender, stirring occasionally. Stir in tomato paste add 7 cups water and beer; stir well. Reduce heat, and simmer for 5 minutes. Stir in cabbage potato, garlic and beets; bring to a boil. Reduce heat and simmer for 20 minutes or until vegetables are tender, stirring occasionally. Remove from heat.
Place in blender to blend. Stir in vinegar, sugar, salt and pepper. Ladle 1 1/2 cups soup into each of 8 bowls - top with 1 tbls sour cream and fresh dill.