Heat the oil in a soup pot over medium heat, add onion, celery
and carrots, and cook until softened, 8 to 10 minutes, stirring
Stir in broth and beans, increase heat to high, and bring to
a boil. Reduce heat to medium-low and cook at a simmer,
stirring occasionally, until beans are tender, 45 to 50 minutes.
Add a touch of water to thin if necessary.
Stir in ham and cook 5 minutes more. Season with salt and
pepper and serve.