Soak the beans by: Placing the washed beans in a bowl. Cover them with cold water. Let them soak overnight or for at least 8 hours.
Or: Placing the washed beans in a saucepan. Add 4 cups water. Bring the beans to a boil. Boil for 2 minutes. Turn off the heat. Let the beans stand for 1 hour.
Drain. Add the broth. Bring to a boil. Reduce the heat to low. Partially cover the pan. Simmer for 2 to 3 hours or until thoroughly cooked. Heat the oil in a heavy skillet. Add the onion and garlic. Cook, stirring, over a low heat, until transparent. Add the celery and carrots. Cook, stirring, for a few minutes longer. Add to the beans. Season with cumin, pepper and salt. Simmer for another 30 minutes. Puree in a blender, food processor or food mill. Garnish with chopped egg and minced scallions. Serve hot.