Score the fat cap in a crosshatch pattern without cutting into the meat. Season all over with coarse salt and pepper.
Heat the grill to high. Place the steak fat-side down and grill for 4 to 5 minutes until the fat renders and browns. Sear the meat side, then move to indirect heat and cook to 130°F (54°C) for medium-rare or your preferred doneness.
Rest and Slice:
Rest the steak on a board for 10 minutes. While it rests, stir together the parsley, olive oil, vinegar, garlic, and pepper flakes.
Slice the picanha across the grain and serve with chimichurri, farofa, and vinaigrette.
Notes
Salt the steak just before grilling for a clean crust.