Using the tip of a sharp knife or a larding needle, make small slits and lard it, alternating bacon strips and truffle slices, distributed evenly over the meat.
Season with salt inside and out.
Preheat the oven to 180°C. Place the leg in a roasting pan, add the lard and pieces of butter on top, and pour 100 ml cold water underneath.
Roast for about 1 hr 15 min to 1 hr 30 min, basting with its own juices every 15-20 minutes, topping up with a little water if needed.
The meat is done when a meat thermometer reads 68-70°C at the thickest part, and the surface is an even, lovely reddish-brown.
Rest for 10 minutes, then carve into thin slices and serve drizzled with the strained pan juices.
Based on: Malatinszky Fanny szakácskönyve (a classic Hungarian cookbook), modernised. Calories and protein are estimated.