Preheat oven to 400ºF (200ºC). Pat lamb dry with paper towel. Mix 1 tbsp (15 mL) oil, garlic, 1 tbsp (15 mL) ginger, chili powder, cumin, pepper, cinnamon and 1 tsp (5 mL) salt. Rub all over lamb. Let stand at least 30 min. or refrigerate 1 hr.
Heat remaining oil in skillet over medium-high heat. Sear roast 5 to 6 min. until golden on all sides. Transfer to roasting pan fitted with rack. Roast 55 min. to 1 hr., or until internal temperature registers 145°F (63°C) for medium-rare or until desired doneness. Let rest 15 min. before slicing.
Meanwhile, make salsa by mixing pineapple, red pepper, onion, vinegar, honey, cilantro, and remaining ginger and salt. Serve with sliced lamb.