Heat oil or butter in a large pot.
Cook leek or onion until softened.
Add carrots and celery and cook 5 minutes.
Stir in garlic and cook briefly.
Add potatoes and barley if using.
Pour in broth to cover vegetables.
Add bay leaf and thyme.
Bring to boil then reduce to simmer for 30 to 40 minutes.
Remove bay leaf and thyme stems.
Adjust seasoning and garnish with parsley.
