Prepare gravy mix in a small saucepan according to packet directions. Stir in cream, vinegar, white wine and peppercorns. Simmer over low heat for a few minutes just to blend the flavours.
Meanwhile, heat a large frypan over medium-high heat. Season steaks with salt and pepper (if desired) and place in the hot frypan. Fry for 7 to 10 minutes per side, or to your desired degree of doneness.
Remove steaks to a serving platter or individual plates and drizzle each one with the gravy.