Make the salsa: In a small saucepan, bring the vinegar and saffron to a boil for 1 minute. Pour into a bowl and whisk in the olive oil slowly allowing it to incorporate and emulsify. Add the olives, lemon, and pepper. Set aside.
Make the lamb: Preheat the oven to 500 degrees F.
Using a knife, make 8 deep slits into the meatiest parts of the lamb. Rub the lamb all over with the oil, oregano, lemon, and salt. Tuck the rosemary and garlic into the slits.
Place the lamb on a rack in a roasting pan and roast until well browned, about 30 minutes. Lower heat to 350 degrees F. and roast about 10 to 15 minutes more per pound. Alternatively, roast until an instant-read thermometer inserted into the thickest part (without touching the bone), reads 130 to 135 degrees F. for medium rare, 140 to 150 for medium. (Add about a cup water to the roasting pan to keep drippings moist, if desired.) Remove the lamb from the oven when it's about 5 degrees shy of preferred doneness. (The internal temperature will rise as the meat rests.)
Transfer the lamb to a cutting board, cover with foil, and let rest for 5 to 10 minutes.
Meanwhile, place the roasting pan over high heat. Pour in the wine, and cook, scraping up the bottom of the pan with a wooden spoon, until reduced slightly. Skim fat from the juices.
Thinly slice the lamb and transfer to a warmed platter. Pour the juices over the lamb and top with the salsa. Serve immediately with orzo or white rice.