To make the marinade, blitz the garlic, chilli and
ginger in a blender until finely chopped. Add the
soy or teriyaki sauce and ketchup, then pulse until
completely blended. Put the beef in a dish and
smear over the marinade. Leave in the fridge to
marinate for up to 24 hours, the longer the better.
To cook the beef, fire up the barbecue and,
when flames subside and coals glow, lay it fat side
down and char for about 5 mins to get fat sizzling.
Flip it over and cook for 40 mins for medium rare,
turning occasionally until all sides are charred. If
the barbecue has a lid, use it for a smokier flavour.
A few mins before taking the beef off, drizzle over
brandy or bourbon (if using) to flambé the meat.
Lift the meat onto a board, cover with foil and
leave to rest for at least 10 mins. Carve the beef
into slices like a roast and serve with any juices.