Heat the oil in a heavy-bottom medium pot.
Add the onion, garlic, thyme, bay leaf, carrot, and celery.
Season with a pinch of salt and pepper and allow the ingredients to sweat. Cook until the onion is soft and translucent, 7-10 minutes.
Add the cooked beans, tomato, and stock and bring to a light boil. Reduce heat to a simmer; the stock will thicken, 30 minutes.
Adjust the seasoning and serve hot.