Remove your joint out of the packaging, pat dry and bring to
room temperature.
Pre heat a griddle or heavy based frying pan large enough to
hold the meat until it sizzles when you add a drop of oil.
Season the beef liberally with sea salt just prior to cooking
& massage with little goose or duck fat.
Sear the beef on all sides over high heat creating a rich, dark
crust then reduce to medium heat.
Cook 8-10 minutes turning frequently then basting the steak
with foaming butter for the final couple of minutes of
cooking.
For a rare beef, press the fillet in the thickest part with
your thumb it should have a slight spring to touch & a core
temperature of 50c before resting.
Alternatively you can pop the beef into a preheated oven (after
the initial charring steps) 200c/80c fan assisted (gas mark 6) for
10-12 minutes.
Leave to rest in a warm place for half the cooking time before
carving.