To prepare the Fasolada (Greek bean soup), place the beans in a saucepan with plenty of cold water to cover. Bring to a boil, turn the heat down to medium and parboil for 30-35 minutes, until slightly tender.
Drain beans in colander and set aside.
Finely chop the onion, celery, and carrots. Add 3-4 Tbsp. olive oil in a deep pan, add the chopped vegetables and blend. Sauté for about 2 minutes.
Add tomato paste and continue sautéing for a minute.
Add the parboiled beans to the pan and pour in enough boiling water to cover the beans and little bit more and blend lightly. Place the lid on and simmer the Fasolada for about 35 minutes, until the beans are tender.
Towards the end of cooking time, pour in the remaining olive oil and season with salt and pepper. Boil for a few more minutes, until the soup becomes thick and creamy.