This is SOOOO good. I make it without the sour cream and it is SOOOO good without the sour cream that it is probably devine with it. Warning: once you start cooking this, you should have your accompaniments ready; the cooking goes pretty fast. I heat up a toaster oven first and when the time comes to keep the steak warm, I turn OFF the toaster oven and pop the steak in (it JUST fits). Combine crushed pepper, butter, and garlic into a paste. Spread evenly on both sides of the steak. Heat oil in heavy frying pan over medium high heat. When very hot, add steak and brown evenly on both sides. Allow 7 minutes per side for rare, 8 minutes for medium rare, and 9 minutes for medium. Place steak on a serving platter and keep warm. Deglaze the pan with the wine and cognac and cook 1 minute. Reduce heat, add cream and chopped parsley and continue cooking 1-2 minutes, stirring constantly. Season to taste with salt. Carve steak diagonally across the grain into thin slices. Pour the sauce over steak and garnish with parsley.