Preheat the barbecue or indoor grill to medium-high heat. Place the mint sauce ingredients in a small pot and bring to a boil. Reduce the heat to lowest setting and let the flavours meld together until the lamb is cooked. Brush the lamb with olive oil and then sprinkle with mint, salt and pepper. Grill 3-4 minutes per side, or until desired doneness is achieved. Serve the lamb with a small cup of the mint sauce alongside.