In a heavy bottomed skillet, melt 1 tbsp (15 mL) butter.
Over high heat, sear steaks 5 minutes each side.
Pour cognac over steaks.
Flambe 30 seconds.
Transfer steaks to a warm serving dish.
Deglaze skillet with wine.
Over high heat, reduce liquid by half.
Meanwhile, in a bowl, mix remaining butter and flour.
Stir kneaded butter and sour cream into wine sauce, mixing until smooth.
Spoon over steaks.