Wash and cut pork fillet into small chunks, boil it in salted water until ready.
Peel onion and celery rut, chop and stew in butter. Combine meat, onion and celery. Season the soup with nutmeg, salt and pepper and cook for more 5 minutes. Remove from heat, add coconut milk and vinegar.
Serve the soup hot, sprinkle with chopped onion.