Put the washed and cleaned pig hearts to boil in water until semi-cooked. Remove them with a slotted spoon and let them cool off. Cut them into pieces.
Preheat oil in a deep pan and fry them until pinking. Add the onion pre-cut into crescents and stir until softened. Add and mix with paprika for 1 minute and top it up with wine, throw in the bay leaf and rosemary.
Simmer the wine for a while and then add salt and black pepper. Once the wine evaporates a bit, the dish is ready.