Thinly slice leeks and soak in cold water for 10 minutes or so, to remove any dirt from between the layers,
then fry in a knob of butter until softened. Season well and add a splash of dry white wine (or dry vermouth).
Simmer for a couple of minutes, then add double cream and continue simmering gently until slightly thickened.
Meanwhile, slice pork fillet into thick medallions and flatten slightly with a meat mallet. Dust in seasoned
flour and fry in butter and olive oil until golden on both sides. Spoon some leek sauce onto warm plates,
top with the pork medallions and accompany with new potatoes and asparagus.