This Sichuan peppercorn spice rub offers an unusual but delicious variation to the usual leg of lamb. The meat goes very well with spring onion pancakes or naan, but, if you don't feel like making those, serve it with cumin-flecked rice pilaf.
Have the butcher butterfly the leg of lamb, so it's of a fairly even thickness. It will never be perfectly even, though, but that's OK because not everyone likes their meat medium-rare, and the thinner parts will be more well done.
If you have time, salt the lamb in the fridge overnight, so the seasoning has time to penetrate into the meat.
Slow-cooking a large cut of meat has the advantage of less shrinkage, and cooking it more evenly. Obviously, though, it takes longer than when roasting it at the more conventional 180° C (350°F) or higher. A slow-cooked leg of lamb will take about six hours to cook. If it's ready before you want to serve it, leave it at room temperature for about an hour or two, then crank up the oven heat and cook the meat briefly, to brown the exterior.
Behind the spice and numbness of Sichuan dishes, lies a dark and bloody history of wars and conflicts. Listen more on Eat Drink Asia podcast about this cuisine of diversity and excitement.
Buy Sichuan peppercorns on the Goldthread shop.
Weigh the lamb, then lay it on the cutting board. Multiply the weight of the lamb by .01 - this is the amount of salt you will need. Sprinkle salt over both sides of the meat, using less on the thinner areas and more on the thicker parts. Place the lamb in a large bowl or on a plate, cover with cling-film and refrigerate for at least an hour (although longer is better).
Make the spice rub. Put the Sichuan peppercorns into a small, unoiled skillet and place it over a medium flame. Shake the skillet constantly to toast the peppercorns until fragrant: they will darken slightly, but do not let them burn. Put the peppercorns into a small bowl and pick and and discard the shiny black seeds, leaving behind the fragrant husks. Toast the cumin seeds and fennel seeds separately the same way, then add them to the peppercorns. Grind the toasted spices to a fine powder in a spice grinder. Mix the ground spices with the sugar, chilli powder and 5g (1tsp) of salt. Crush the garlic cloves to a rough paste and mix with the other spice mixture. Add enough oil so the mixture forms a thick but spreadable paste. Rub the paste over the lamb, using less on the thinner areas and more on the thicker parts. Keep at room temperature for an hour or two
Preheat the oven to 100°C (210°F). Place the lamb fat side up on a flat rack in a roasting pan. Insert a probe-type meat thermometer (preferably an electronic one) into the thickest part of the lamb leg and programme it to go off when it reaches 53°C (127°F) for medium-rare, or set it at the doneness you like. Place the lamb in the oven and cook until it reaches the correct temperature. Take the pan from the oven and leave the meat to rest at room temperature for about 20 minutes. Turn the oven temperature to 250°C (480°F) then place the meat back in the oven. Cook until the surface is sizzling and lightly charred in spots, watching it carefully so it doesn't burn too much. Carve the meat against the grain and serve.