Preheat the oven to 200C/400F/Gas 6.
For the steak Diane, heat the oil in a frying pan and fry the shallots and mushrooms over medium heat for 3-4 minutes, or until softened.
Turn up the heat and fry the steak pieces in the pan for 1-2 minutes on each side, stirring the mushrooms and shallots from time to time to prevent them from burning.
Pour in the brandy and cook for 3-4 minutes, or until the liquid has reduced by half. Stir in the cream and peppercorns. Season, to taste, with salt and freshly ground black pepper. Turn down the heat and simmer for 2-3 minutes, or until the sauce has thickened.
For the chips, heat the vegetable oil in an ovenproof frying pan, add the potatoes and curry powder and fry for 2-3 minutes. Season, to taste, with salt and freshly ground black pepper.
Place the pan into the oven for 6-8 minutes, or until the chips are golden-brown and cooked through.
To serve, place the steak on a plate with the chips to one side and the rocket leaves and cherry tomatoes on top. Drizzle over the sauce.
