Heat the oil in a large soup pot on low heat.
Add the chopped onion, carrot and celery. Lightly season with salt and pepper. You can add more seasoning at the end. Cook for 3 minutes or until the onions are translucent.
Add the garlic and tomato or tomato paste. Cook for an additional minute.
Stir in the vegetable broth and miso. Add the fresh parsley, thyme, bay leaves and red pepper flakes.
Cover and increase the heat to quickly bring to a boil then lower the heat once more to a slow simmer for 15 minutes.
Stir in the cooked barley. Add more water if needed. Continue cooking for an additional 5 minutes.
Taste and adjust the seasonings to your liking. Remove any thyme stems and bay leaves.
Remove from heat and serve.
