In a medium-large pot over medium-high heat, add a drizzle of vegetable oil and heat until shimmering, about 2 minutes.

Add 1 cup of chopped onion, 1 teaspoon of minced garlic, and 1 cup of thinly sliced carrots to the pot. Sauté for about 4 minutes.

Incorporate 2 cups of thinly sliced brown mushrooms into the pot and sauté for an additional 3 minutes.

Stir in 1 cup of pearl barley, mixing well. Pour in enough water to cover the ingredients, about 5-6 cups. Add 1.5 tablespoons of vegetable stock powder, 2 teaspoons of salt, and 1 teaspoon of ground black pepper.

Raise heat to high to bring to a boil, then reduce heat to low and cover. Let it simmer for about 1 hour.

For a slow cooker version, transfer sautéed vegetables to the slow cooker, add water and barley, cover, and cook on low for 6-7 hours.

Once ready, ladle the soup into bowls and garnish with finely chopped fresh parsley.