Score the fatty blanket on the picanha by making criss-cross cuts into the thick layer of fat covering one side. Cut the piece of picanha into 4 to 5 thick pieces of about 250g to 300g each about 5cm thick, keeping the fat covering the upper surface of each steak.
Place the steaks on a tray and cover them thoroughly in the rock sea salt, this will help to seal in the juices of the meat. Table or cooking salts are too fine and more of them will be needed to do the same job resulting in a very salty barbecued picanha, so do stick to rock salt for this recipe. In addition, rock salt does not penetrate nearly as much as finer salts, giving a delicious and lightly salty crust to the meat. If your salt tolerance is low, you may prefer not to salt the beef and only use the dressing to season it as it is served.
Now make the soy & yuzu or lime dressing by mixing together the soy sauce, olive oil, yuzu or lime juice, crushed garlic cloves and ½ of diced red chilli – this dressing will be used for basting the meat while on the grill and the other ½ will be used as a dipping sauce to serve with the slices of beef.
BBQ Method: Get your barbecue hot and ready for the picanha, and generously brush the grill plates with oil. Grill the picanha pieces fat-side up for a few minutes until a little juice leaks out of the steaks. Turn the steaks onto their sides to grill for a few minutes more on each side. Using a brush, baste the meat with the reserved ½ of soy and yuzu lime dressing every time your turn the steaks. Finally grill fat-side down, moving the steaks away from the hottest part of the fire to avoid over-cooking and to reduce the chance of the fire flaring up from the dripping fat. Grill to your desired doneness, it should take anything from 15 to 25 minutes depending on the thickness of the steaks and how fierce the fire in your barbecue is. I use the ‘finger poke method’ to know when the meat is done – I like my picanha rather pink, so the meat should feel bouncy but firm cooked for about 15 to 20 minutes in total. Alternatively, you can take one steak out of the grill and cut a small piece of it from its thickest part to check for doneness.
Kitchen Grill Method: If you don’t have a barbecue you can still cook the picanha under a hot grill in your kitchen. Place the steaks over a rack within a roasting tin, this is important as the picanha’s fat will drip into it and not in your oven. Grill the steaks for 7 minutes flesh side up, then turn them over and grill fat side up, preferably on a lower rack or at the bottom of the oven, for another 8 to 12 minutes, basting the beef with the reserved ½ of soy and yuzu lime dressing for 2 minutes before the end of cooking time. If using the kitchen grill, a meat thermometer read is more accurate than on the barbecue – the internal temperature of the meat should be 60°C for rare, 63°C for medium rare, 71°C for medium and 77°C for well-done. If you don’t have a meat thermometer, use the finger poke method described above.