Cut trimmed artichokes into thin wedges. Heat oil in a large soup pot over high heat. Add the artichokes, leek, potato, celery and bay leaf; saute until the leek starts to wilt, 3 to 5 minutes. Add broth, and bring to a boil. Cover, reduce heat to low and simmer until potatoes and artichokes are tender, about 30 minutes. Remove from heat and discard bay leaf. Let the soup cool for 5 minutes.