I dragged a lamb loin roast out of the freezer and played with it.
First the bone was removed.
The roast was dusted with meat glue and rolled.
After resting 24 hours in the fridge it had a 57°C bath for 5 hours and then torched to render and crisp the fat.

The photo doesn't show it clearly but there is a swimming pool of liquid fat under the roast. Even after torching the fat for almost 10 minutes the fat was still not fully rendered. Next time the roast will be boned, rolled, tied and cooked in a low oven until done.