Beef medallion is an American name for what is more commonly called filet mignon. A beef medallion is a circular or square, thick (2.5cm/1 inch or more) piece of steak cut to fit squarely on the plate, and easy to cook however you prefer it, from rare to well done, and all stages in between. It usually comes in two forms: A grilling medallion is cut from top sirloin, rib eye or strip loin. A marinating medallion is cut from the inside round, cross rib or sirloin tip.
Use grilling medallions cut from top sirloin, ribeye or strip loin. Rub salt and pepper and/or your favourite herbs and/or steak seasoning all over the medallions. Set aside.
Pour enough oil (or half oil and half butter) to cover the bottom of a stainless steel frying pan. Heat until the oil is sizzling, but not smoking. Using tongs, place medallions into pan. Add more butter and/or oil, if needed. The average cooking time for a medium done steak is about 6 to 8 minutes on each side, less time for medium rare and more for medium well or well done.
Flip the medallions over and brown on the other side. Remove medallions from pan and cover loosely with foil. Immediately start preparing the pan sauce.
Add chopped onions and garlic to the same pan the meat was browned in, then add your favourite herbs and seasonings, a little more oil and butter, if needed. Stir in beef or vegetable stock and a splash of your favourite wine. Using a wooden spoon, deglaze the pan by stirring up the brown bits.
Cook and stir about 5 minutes, or until thickened and slightly reduced. Remove from heat, pour the sauce into a small bowl and serve on top of or alongside the medallions.
Wearing an apron while preparing medallions is highly recommended to avoid oil splatters on your clothes.