You need to buy a boned-out midloin of lamb to make these. This is a rack of lamb with the bone out, but the flap left on. It is sometimes sold as a lamb loin roast.
Trim as much fat as possible from the skin side of the cut but go carefully over the flap. It needs to remain intact to allow you to roll the meat, as you would a Swiss Roll.
You need a sharp smallish knife to do this, a boning knife is ideal, or ask your friendly local butcher to prepare this part for you.
For four people you need around 1kg of lamb.
Blend together:
2 tbsp of oil
2 tbsp of honey
1 clove of garlic (optional)
A thumb-sized chunk of peeled fresh ginger, grated.
The zest and juice of 1 lemon.
1 tbsp of fresh thyme leaves.