Thaw the meat completely, place it on a cutting board, and rub it with salt on all sides. Cut slits on top with a knife and tuck a garlic clove into each one.

Coat the meat generously with mustard on all sides, wrap tightly in foil, and roast in an oven preheated to 200°C for 1.5-2 hours.

Leave the meat in the oven until it cools completely, then move it to the fridge. Slice thin before serving.