Trim the excess fat from the steak and score the edges to prevent it from curling when cooked. Dry the steak with paper towels and press into the meat the cracked peppercorns.
In a heavy skillet, heat the butter with the oil. When very hot, but not burning, put in the steaks and without moving them around cook over medium high heat on each side until moderately firm to the touch. Turn with tongs.
Remove the steak from the pan and keep warm on a heated plate. Pour off any fat in the pan being careful to save the meat juices. Pour in the Cognac (or brandy) and simmer. Add the cream. Taste and add salt and pepper to taste. Slice the steak and pour over the
sauce. Garnish with watercress.