Place a deep pot over a medium-high heat, pour in some olive oil, add onions and carrots, mix with a wooden spoon, and sauté for 2-3 minutes.
Add the celery. If the pot has dried out, add a little more olive oil, and sauté for 1 more minute.
Add the garlic to the pot, sauté again for 1 minute and once the vegetables are caramelized, add the tomato paste. Stir for 2 minutes.
Then, add the strained beans, diced tomato, bay leaves, and stock and mix. Cover the pot and boil for 1 to 1½ hours.
Uncover the pot and boil for another 20-30 minutes.
When the beans are ready, remove the pot from the heat, add the parsley, salt, pepper and mix.
Serve hot, accompanied by feta cheese and toasted bread.