roast lamb with a pistachio, apricot and lemon crust

I harbour a secret desire to know the intricacies of roasting meat to perfection.  Do some cooks just know how to do this?  Or is it purely a matter of cooking time, juggling with ovens and thermometers. I have witnessed professional chefs mopping frazzled brows as they put the thermometer into the lamb at a crucial moment only to find it is not hot enough! Mon dieu and what is to be done with all the waiting guests!  I still don't know the correct temperature and have never done it this way, I guess safer if you enjoy meat rare and people are paying for your food. I decided to cook a leg of New Zealand roast lamb.  Heston's recipe as below, was followed to the letter, but as my leg was 1.7kg it was cooked a little too much. Nigel Slater's suggestion for roast lamb medium rare is - 20mins at 220C, then about 15 minutes per 450g of meat and 10 minutes resting. Will try these cooking times in future, but the recipe was absolutely drop dead DELICIOUS and doesn't require a wink of adjustment otherwise!


ROAST LAMB WITH A PISTACHIO, APRICOT & LEMON CRUST
1.8-2kg leg of lamb
3 cloves garlic sliced
1 tbsp olive oil
50g dried apricots
50g pistachios
4 tbsp freshly ground parmigiano reggiano
grated zest and juice of 1/2 lemon
Preheat oven to 200C. Place lamb in a roasting tin and pierce all over with a small sharp knife. Insert slivers of garlic into piercings. Rub skin with olive oil and season. Roast in oven for 30 minutes then reduce temperature to 180C for a further hour.
While the lamb is cooking, whizz the apricots and pistachios together in a blender until finely chopped. Stir in cheese, lemon zest and juice and season.
Remove lamb from oven, press the mixture all over the lamb, baste with tin juices and return to the oven for a further 15 minutes until the crust is golden brown.
Remove lamb from oven, place on a warm platter and leave to rest for 10 minutes.  Make lamb gravy from tin juices by adding lamb stock or whatever else takes your fancy. Cut the lamb in glorious chunks and serve with gravy and fresh spring vegetables or a zesty salad!  I lightly steamed some french beans and tossed together with a little rocket, few sprigs of coriander, mint and parsley, pomegranate seeds and the zest and juice of one lime, olive oil, little sprinkle of grated parmigiano reggino and some seasoning. Bon apetit!