For Chimichurri: Combine ingredients for Chimichurri and set aside.
For peppers: place on grill, cook for 20 minutes, turning, as each side blackens and they start to collapse. Remove from heat, place on a serving plate and drizzle with olive oil and balsamic.
Bring rump to room temperature 30 minutes before cooking. Sprinkle with rock salt all over. Skewer rump. Add the meat skewer to a rotisserie grill, allowing the meat to turn. Otherwise, place it on the barbeque grill, over medium heat, with the fat side down.
Cook the meat to you reach desired doneness. If using a barbeque, turn regularly and monitor temperature. Tap skewer to knock off any extra salt. Remove from heat and cover loosely with foil, rest for half the cooking time.
Serve with chimichurri sauce, roasted bell peppers and a green salad.
When cooking to the desired doneness, it is best to probe the meat with a thermometer. Check our cooking conversion times for an indication of desired doneness, temperature and cook time.
For chimichurri, a food processor or blender can be used. Place all ingredients except oil in a food processor or blender, process until combined. While motor is running pour in oil in a thin steady stream until combined.