In a pestle and mortar, crush peppercorns
and garlic with a pinch of salt until you have
a smooth-ish paste, then stir in the vinegar.
Sit the beef in a non-metallic dish, then rub
all over with the paste. Leave in the fridge
for a few hrs, but no longer.
To cook, place a griddle pan over a very
hot heat. Rub the marinade off the meat,
then season with a little more salt. Cook
meat until charred on each side – about 5
mins on each side for rare; if the cut is very
thick, you may want to roast it in a hot oven
for 5 mins after searing. Lift onto a chopping
board, then rest for 5 mins before carving
into slices and serving with chips, if you like.