Preheat oven to 200ºC (390ºF). Combine 2 tablespoons olive oil with the lemon juice, garlic, rosemary, salt and pepper in a bowl. Brush half the mixture onto the lamb cutlets, cover and set aside for 20 minutes. Place the potato in a baking dish with remaining oil, sprinkle with salt and toss to coat. Roast for 30–40 minutes or until tender and golden. Add white beans and toss gently to combine.
Heat a char-grill pan over high heat. Char-grill the lamb for 2–3 minutes each side for medium-rare or until cooked to your liking. Arrange potato, beans and spinach on plates, top with the lamb and spoon over the remaining oil mixture to serve. Serves 2.