1-kilogram piece of beef rump cap (aged 3 months is ideal)
1 tablespoon grapeseed oil, plus extra for brushing
1 tablespoon lime juice
1 tablespoon coriander seeds, crushed
1 tablespoon cumin seeds
1 tablespoon salt
2 teaspoon fresh oregano
2 teaspoon chipotle powder
1 teaspoon freshly grated ginger
1 teaspoon black peppercorns
1 teaspoon chilli flake
1 teaspoon dried mint
½ teaspoon ground turmeric
2 bunches (60 grams) fresh parsley
1 bunch (25 grams) fresh oregano
4 garlic cloves, peeled
120ml (½ cup) apple cider (or juice)
½ apple, peeled, cored and chopped
1 tablespoon apple cider vinegar
1 whole fresh red jalapeño or other chili pepper, seeded and chopped
120ml (½ cup) extra virgin olive oil
Combine the rub ingredients together in a small bowl.
Pat the beef dry using kitchen paper. Score the fat, making incisions about 1cm deep, 5mm apart. Brush with oil to coat. Pack the rub into the fat on top of the beef, then cover and chill for 2 hours. Remove the beef from the fridge at least an hour before cooking to let it come to room temperature.
Make the chimichurri Argentina. Put all the ingredients except the oil in a food processor, or small blender, and pulse until coarsely chopped. Slowly drizzle in the oil until combined, adding more if you wish. Spoon into a serving bowl, cover and chill until needed.
Turn on the extractor fan, then heat a stovetop grill pan/plate or barbecue to medium–high, place the beef on it, fat-side up, and cook for about 6 minutes, then carefully turn it over and cook fat-side down for an additional 6–8 minutes. Test for doneness with a thermometer if you like (it should have reached 55°C for rare/medium–rare).
Remove from heat and transfer to a carving board. Loosely cover with foil and let rest for 15–20 minutes. Thinly slice the beef across the grain and serve with the chimichurri Argentina.
Cook's note: You can apply the rub to the beef up to two days ahead and the sauce, too, can be made a day in advance.