1. Preheat the oven to Gas mark 6, 200°C, 400°F.
2. To prepare the potato slices; boil the potatoes in salted water for 10-15 minutes.  Drain and cool slightly.  When cool enough to handle slice to the tickness of a pound coin and transfer to a large bowl.
3. Add the melted butter, season and toss gently.  On a foil lined shallow baking tray or roasting dish arrange four 8cm / 3¼ inch cakes in a single layer of overlapping slices.  our over the stock and bake for 15-20 minutes or until tender and most of the stock has evaporated. 
4.   Meanwhile, melt half of the remaining butter with the oil in a non-stick griddle or frying pan.  Season the fillets and cook according to your preference.  Remove, transfer to a warm plate, cover and set aside to rest. 
5.   Add the shallots anbd mushrooms to the same pan.  Add the Armagnac or brandy.  Cook for a further minute then add the stock and thyme.  Bring to the boil, reduce the heat and simmer for 4-5 minutes or until reduced by half.  Whisk the remaining butter into the sauce.  Remove the thyme sprigs. 
6. Arrange the potato cakes on a warm plate, top with the beef and spoon over the sauce.  Garnish with the redcurrants ans serve with seasonal vegetables. 

Tip:  If preferred, use rib-eye steaksas an alternative to fillet steak but reduce the cooking time by about a minute on each side. 

Reproduced with kind permission of EBLEX.