Pour olive oil into a pot, turn heat to medium. Once oil is hot, add celery, onion, carrots and garlic, cook for 6-8 minutes.
Add chickpeas and broccoli to pot, cook for 2 minutes.
Pour 4 cups of water into pot, bring to a boil. Reduce heat and simmer vegetables for 10 minutes.
Dissolve miso in remaining water, add to soup pot, stir together and season with salt.