Prepare the porcini mushrooms ahead – soak in cold water for about 3 hours.
Strain over a sieve, pressing out the solids; but hold on to the liquid.
You can also prepare the barley in advance. In a medium saucepan bring 1 cup of water to a boil; add 1 cup of barley and cook for about 10-15 minutes.
Next, make the mushroom broth.
A homemade broth is the secret base of many favorite Slavic soups.
Place the soaked mushrooms into a pot. Add 6 cups of water and the remaining liquid from the porcini.
Add a whole peeled onion, 1 tablespoon of salt, and 2 bay leaves.
Bring the broth to a boil, then skim off the foam and discard.
Let the broth simmer on low heat for 35-40 minutes.
Meanwhile, heat 3 tablespoons of vegetable oil over medium heat in a large skillet, and then add fresh porcini mushrooms.
Season with salt, and cook for about 10 minutes.
Stir occasionally until the mushrooms are golden.
Add garlic, Vegeta, and stir again.
Top with dill, and cook for another 3-5 minutes.
Add seared porcini to the pot, and stir.
Add the diced potatoes, increase the heat to medium and cook for 15 to 20 minutes until the potatoes are fork-tender. Add the pre-cooked barley to the soup.
Serve with sour cream and herbs.