Wash dried mushrooms under running water. I used a mix of Porcini and Oyster mushrooms. Soak them in water for 1 hour.
Drain the water and chop the mushrooms into small pieces. Reserve the water in which we soaked them.
Transfer the chopped mushroom to a large pot along with the reserved water. Add vegetable broth, salt & pepper to taste, and pearl barley to the pot and bring the soup to a boil over high heat.
Reduce the heat to low. Cover the pot with a lid and cook the soup on low heat for 30 minutes.
Add peeled and cubed potatoes and cubed carrots and cook covered for another 30 minutes. Remove the pot from the heat and set it aside.
Heat light olive oil in a medium skillet over medium-high heat. Once the oil is hot, add minced garlic and chopped onions and fry until they turn slightly brown.
Pour the onions over the soup and serve hot.