Pre-heat grill. Cut steak into 1.5 inch cubes, taking care to remove large fat wedge if present. Drizzle cubes with olive oil and toss to coat lightly – just enough to coat in a thin layer. Sprinkle with sea salt and a generous amount of cracked pepper medley and toss to distribute evenly.
Cut sweet onions into 1-1.5 inch wedges, one to two layers thick. Thread meat and onion alternately onto skewers.
Clean cooking grate and brush or mist with olive oil. Grill brochettes over hot coals to brown, taking care to remove at rare to medium rare. Cover with a clean towel and rest for 5 minutes, serve drizzled with Balsamico di Modena, a sweet balsamic glaze from Modena Italy and serve.
