Step 1

Make the spice rub. Toast cumin seeds and coriander seeds in a dry skillet over medium low heat, stirring frequently, for 5 or so minutes, until fragrant. Transfer to plate and let cool thoroughly. Grind cumin, coriander and peppercorns with a mortar and pestle or in a spice grinder. Combine the cumin mixture in a bowl with the remaining rub ingredients, through olive oil, stirring to thoroughly blend.

Step 2

Spread the rub evenly over the entire surface of the leg of lamb. I spooned it on, then used my hands. Wrap the leg of lamb in plastic wrap and marinate, chilled, for 4 hours or longer. Remove from fridge for last half-hour of marinating to let it warm up slightly before roasting.

Step 3

Roast the leg of lamb. Preheat the oven to 350ºF. Lightly oil a baking pan [just to make it easier to clean later] and place the leg of lamb in a rack in the pan. Roast in the center of the oven for 15 to 20 minutes per pound, rotating the pan once halfway through.

Step 4

Variations in ovens and the size of the leg of lamb will cause cooking times to vary quite a bit. Use a quick-read thermometer to check the lamb well before you think it should be done (make sure you don't hit the bone—that will give you an inflated reading). You're shooting for an internal temperature of anywhere from 130 to 145ºF.

Step 5

Remove from the oven and let it rest, tented lightly with foil, for 10 minutes before slicing and serving.