In a large soup pot (larger than 2 Qt) saute chopped onion and diced garlic in 1/4 c vegetable broth over medium heat until tender, about 5 minutes.
add chopped carrots & celery, cook 3-5 minutes.
Add sliced mushrooms, cook 5 minutes.
Add seasonings, chopped parsley, balsamic vinegar, remaining vegetable broth and barley.
Bring to a boil.
Reduce heat, cover and simmer for 45 minutes or until the barley is tender.
Add 2 cups of fresh spinach and cook 2 minutes.
Add 1-2 cups of water to reach desired soup consistency.
Optional garnish with fresh parsley.
I got fancy and kept a few sliced of portobello aside, I cooked them in balsamic vinegar & liquid aminos in a frying pan for a few minutes per side and garnished my soup with the portobello slices.
Makes 4-6 servings depending on how much water is added.