First make the soured cream sauce by placing all the ingredients in a small bowl. Stir well and set aside or chill until needed.
Preheat the oven to 220ºC/200ºC Fan/Gas Mark 7. In a large bowl mix together all the ingredients for the meatballs, bar the sunflower oil. Once evenly mixed, shape into burgers, about 45g each, making about 18.
Pour enough sunflower oil into a large frying pan so you get a thin layer at the bottom, about 2mm thick. Heat up well and sear the meatballs in batches on medium heat from all sides. Cook them for about 4 minutes, adding oil as needed, until golden brown.
Carefully transfer the seared meatballs into an oven tray lined with greaseproof paper and place in the oven 5-7 minutes, or until just cooked through. Serve warm or at room temperature, with the sauce on the side.