1. Soak 20 halved lamb's kidneys in vinegar and water for 1 hour, remove, drain and dry.
2. Fry 100 g chopped onion and 3 chopped cloves of garlic in 80 ml olive oil, add and saute the kidneys, then stir in 30 g paprika, 75 g breadcrumbs and 1 tsp marjoram; when cooked, transfer the kidneys to a serving dish.
3. Add 100 ml dry sherry and 500 ml brown stock to the pan, reduce to a sauce consistency and season.
4. Replace the kidneys in the sauce and serve sprinkled with chopped fresh herbs.