Ingredients

• 1-ounce (30 g) dried porcini mushrooms
• 2 tablespoons vegetable oil
• 1/2 pound white mushrooms, trimmed, wiped clean, and sliced 1/4 inch thick
• 1 large onion, cut into 1/4-inch dice
• 10 small or 7 to 8 medium beets, with greens, peeled, quartered, and cut across into 1/4-inch slices
• 2 medium carrots, peeled and cut across into 1/4-inch rounds
• 1 medium parsnip, peeled and cut across into 1/4-inch rounds
• 1 very small or 1/2 large celery root (about 3/4 pound), peeled and cut into 1/2 inch cubes
• 1 1/2 pounds mashing potatoes, peeled and cut into 1/2-inch cubes
• 1/2 small white cabbage (about 3/4 pound), cored and shredded
• 3 large cloves garlic, smashed, peeled, and very finely chopped
• 3 tablespoons tomato paste
• 1 medium bunch dill, fronds only, coarsely chopped
• 1/4 cup sugar
• 1/2 cup cider vinegar
• 2 tablespoons kosher salt
• Freshly ground black pepper, to taste
• Coarsely chopped dill
• Sour cream
• Boiled potatoes, optional

Instructions

1. Soak the dried mushrooms in 1 cup hot water for 15 minutes. Drain, reserving the liquid, and squeeze out the excess liquid. Strain all the soaking liquid through a fine-mesh sieve. Reserve the liquid (there should be 1 cup) and the mushrooms separately.
2. In a tall narrow stockpot, heat the oil over medium heat. Stir in the fresh mushrooms and cook, stirring occasionally, for 4 minutes. Stir in the onion and cook, stirring occasionally, for 8 minutes.
3. Add the beets, carrots, parsnip, celery root, 8 cups water, and the mushroom soaking liquid. bring to a boil. Lower the heat and simmer for 5 minutes. Stir in the potatoes, cabbage, garlic, and, if using, the beet greens. Dissolve the tomato paste in 1/2 cup of the liquid and stir back into soup. Return to a boil. Lower the heat and simmer for 5 minutes. Stir in the reconstituted mushrooms and simmer for 5 minutes, or until all the vegetables are tender.
4. Remove from the heat. Stir in the dill, sugar, vinegar, salt and pepper.
5. Pass bowls of chopped dill and sour cream at the table.