Soak the beans in water overnight. The next day, throw out the water, pour in new water and put to boil. Throw out this water too. Pour new water over the beans, salt them, add the bay leaf and black pepper. Boil until softened.
In the meantime, saute the onions with 3 tbsp olive oil. Add the boiled and drained beans to it. Sprinkle black pepper and paprika and cook for another 5-10 min.
Fill the cleaned peppers with the thick beans and arrange them tightly next to each other in a clay pot. Pour on the remainder of the beans in between them, pour on the last 2 tbsp olive oil and bake in a preheated 428°F (220 °C) oven.