For the chips, preheat the oven to 180˚C. Wash the potatoes well and peel them. Wash again under running water, cut into thick chips. Place in a large saucepan of cold water and add the salt and vinegar. Bring to a low rolling boil and cook for 5 minutes to bloom the starch. They should be tender but not falling apart. Carefully drain the chips and allow to steam dry for 10 minutes.Spray a heavy-based roasting pan with olive oil spray (or just drizzle with oil), then place in the oven to preheat. When hot, add the chips in a single layer and spray liberally with oil. Roast for 40-50 minutes or until golden and crisp. Season with extra salt. When the chips are nearly done, using a rolling pin, roll out the steaks to flatten, then season on both sides with salt and pepper. Heat a little olive oil in a large frying pan over high heat. Cook the steaks for 2 minutes on each side, then remove from the pan and set aside to rest. Reserve the pan. To make the Diane sauce, return the pan to medium heat. Add the butter and when melted, add the shallots and stir for 1-2 minutes or until just softened. Add the mushrooms and stir to combine well, then add the garlic, Worcestershire sauce and mustard and heat through for 1 minute. Turn up the heat and tilt the pan away from you. Pour the brandy into the far end and allow it to ignite. Once the alcohol has burnt off, swirl the juices around the pan. Add the cream and allow the sauce to thicken before turning down the heat.Return the steaks back to the pan and cook a little further depending on how well done you would like them. Stir in half the parsley and remove from the heat.  Divide the steaks between serving plates, spoon the sauce on top, sprinkle with the remaining parsley and serve with the chips.  Photography by Adam Liaw.Want more from The Cook Up?• Stream free here at .• Get the show recipes, articles and more.