Heat the oil in a medium-large pot over medium-high heat for about 2 minutes until shimmering.

Sauté the chopped onion, minced garlic, and sliced carrots for about 4 minutes until soft.

Add the sliced mushrooms and sauté for another 3 minutes until softened.

Incorporate the barley and enough water to cover all ingredients by about 4 inches. Stir in stock powder, salt, and pepper.

Bring the mixture to a boil, stirring occasionally.

Reduce heat, cover, and let it simmer for about 1 hour until the barley is tender.

For a slow-cooked version, transfer the sautéed mixture to a slow cooker, add water, barley, and seasonings. Cook on low for 6 to 7 hours.

Serve warm, garnished with fresh parsley.