Cover the cutlets with the combined lemon juice, oregano and crushed garlic. Set aside to use later.
Peel and cut the sweet potato and new potatoes into even shape and size. Place in a saucepan, cover with cold water and add a pinch of salt. Boil until soft, drain off all water and mash together with butter and milk.
Preheat a non-stick frypan to moderately hot. Cook the cutlets on one side until the first sign of moisture appears. Turn and cook for a further 2 min for medium-rare or until desired degree of doneness.
Remove the cutlets from the heat, cover loosely with foil and rest cutlets for 2 min before serving.
Serve the cutlets on sweet potato mash. Serve with steamed vegetables..