Place all marinade ingredients into a bowl and and toss to combine. Cover and let marinate for at least 1 hour.
To make the dressing, place all ingredients into a bowl and stir well.
Cook the beef in 2 batches (discarding any excess marinade).
Place 250 grams beef at a time and cook 5 min/browning/gentle. Tip out into a thermoserver to keep warm.
Repeat with remaining beef.
Add the onions and garlic to the cooked beef and toss to combine.
To assemble, place rocket on a serving platter, top with beef and drizzle with the dressing.