Mix salt, pepper, oregano and garlic powder in small bowl. Rub spice mixture on all sides of lamb chops. Place lamb chops in large glass baking dish. Cover; chill at least 4 hours or overnight. Prepare barbecue (medium-high heat). Grill lamb chops to desired doneness, about 4 minutes per side for medium-rare. Place 2 double lamb chops on each of 4 plates. Place potatoes alongside; drizzle some lemon vinaigrette over lamb. Garnish with lemon wedges.