Put the cleaned beans to come to a boil in 8 1/3 cups (2 L) water, then boil another 15 min. Remove the beans, drain the water and in the same container, pour in 12 1/2 cups (3 L) of hot water, return the beans and boil another 90 min. uncovered.
Braise the flour in the oil until golden, sprinkle with paprika, stir a little and dilute with a little broth from the soup.
Stir and thicken the bean soup with this mixture. Leave to boil another 5 min., then remove and add finely chopped spearmint and parsley.