Trim the venison fillet of all membrane and sinew, and cut into slices (about 1.5-2 cm thick).
Lard the slices with thin strips of bacon using a larding needle.
Place in a bowl, drizzle with the lemon juice, brush with the melted butter, cover and let stand in the fridge for 4-5 hours.
Wrap the slices in buttered baking parchment.
Scatter sliced carrot, parsley root, bay leaves, whole peppercorns, ginger and a strip of lemon zest in a roasting pan, and place the wrapped meat on top.
Place in a preheated 180°C oven and roast for about 1 hour, basting occasionally with the juices collecting under the paper.
About 45 minutes before serving, unwrap the paper so the bacon browns nicely.
Brush with 3 tbsp sour cream, and return to the oven for the last few minutes.
Arrange neatly on a platter, and serve drizzled with the strained pan juices.
Based on: Malatinszky Fanny szakácskönyve (a classic Hungarian cookbook), modernised. Calories and protein are estimated.