Mix the chilli powder, cumin, coriander and oregano together with a good grind of black pepper and a pinch of salt. Rub the oil over the steak, then rub with half the spice mix. Set aside to marinate for 30 mins. Meanwhile, combine the remaining spice mix with the vinegar, parsley and butter, and set aside.

Heat a griddle pan over a high heat, then cook the steak for 3 mins on each side for rare, 4 mins for medium-rare or 5 mins for well done. Transfer to a board or plate and leave to rest. Meanwhile, griddle the corn, turning, until lightly charred on all sides. Spoon half of the flavoured butter over the steak, then use the rest to baste the corn. Season the chips with sea salt, if you have it, then serve with the steak, corn and some green beans.