In a large saucepan cook leeks in hot oil over medium heat for 3 minutes or just until tender. Remove a few leeks with a slotted spoon and set aside. Stir in soup, juice, carrots, ham, and pepper. Bring to boiling. Reduce heat and simmer, covered, for 15 minutes or until carrots are tender.
Ladle into serving bowls and top with reserved leeks and, if desired, mint.