Sauté the Aromatics: Heat 2 tablespoons of vegetable oil in a pot over medium-high heat. Add 1 chopped onion, 2 minced garlic cloves, and 2 chopped carrots. Sauté for about 4 minutes until the onion becomes soft.

Cook the Mushrooms: Stir in 8 ounces of sliced brown mushrooms, cooking for an additional 3 minutes until browned and fragrant.

Add the Barley and Liquid: Add 1 cup of barley and stir. Pour in enough water (5-6 cups) to cover the mixture by about 4 inches.

Season the Soup: Sprinkle in 2 tablespoons of vegetable stock powder, along with salt and pepper to taste. Bring to a gentle boil.

Simmer to Perfection: Reduce heat to low, cover, and simmer for about 1 hour until the barley is tender, stirring occasionally.

Optional Slow Cooker Method: Transfer sautéed vegetables to a slow cooker. Add barley, water, and seasonings, cover, and cook on low for 6-7 hours.

Garnish and Serve: Ladle soup into bowls and garnish with freshly chopped parsley. Serve hot.