Gently flatten the lamb fillet with the palm of your hand or a bottle. Heat a grill pan, brush the meat with the oil and seal on both sides. Season with pepper and place in warm oven for 10 minutes to cook through.
While the lamb is cooking, gently heat the olive oil and garlic and add the cannellini beans. Stone the plum and cut it into small chunks. Stir the plums through the cannellini beans to heat through. Season and serve under the lamb with accompanying steamed green beans.
Note: Once opened, store the remaining cannellini beans in a plastic container covered with fresh water, store in the refrigerator and use within a few days.
Makes 1 servings