Remove the rack of lamb from the fridge half an hour before cooking. Preheat the oven to 140°C (120°C fan, gas 2).
Peel the garlic.
Wash the thyme and pat dry.
Peel the ginger and cut into fine strips.
Heat 1 tablespoon oil in an ovenproof pan.
Fry the lamb rack on both sides over a medium heat for 3 minutes until nicely browned. Place the meat on a rack over a roasting tin and roast for 15 minutes.
Add 1 tbsp oil and the garlic, thyme and ginger to the pan the meat was browned in.
Stir-fry, adding the spices during cooking.
Remove the lamb from the oven and, after adding the butter, fry again in the pan on both sides. Add salt and pepper.
Let the meat rest briefly. Cut in between the bones and serve garnished with rosemary.