Peel and finely dice the onion and garlic. Puree the tomatoes with a blender. Pour beans into a sieve, rinse with cold water and drain well. Clean and wash spring onions and cut into fine rings.
Cut the sausage into long thin slices. Clean, wash and halve the tomatoes. Heat oil in a pot, fry sausage briefly in it and take it out. Add onion to the oil and fry until transparent. Add garlic, oregano, spring onions and tomatoes, fry briefly.
Add tomato paste, sweat briefly, deglaze with stock and pureed tomatoes. Bring to the boil. Simmer at low heat for about 5 minutes. Add beans and sausage 2 minutes before the end of cooking time. Season soup with salt, pepper, paprika and sugar.
Serve garnished with oregano as desired.