Sit a steaming basket on a wide-bottomed pan. Fill the water until just below the base of the basket. Place the broccoli in the steaming basket, season with salt. Cover and steam over a medium heat for approx. 10 mins. ensuring the broccoli is still a little crunchy, allow to cool slightly. To make the vinaigrette, mix the lemon zest with all the other ingredients up to and including the onion, season. Mix the warm broccoli with the vinaigrette, cover and leave to marinate for approx. 30 mins.
Heat the griddle pan and brush with oil. Grill the meat in batches over a high heat for approx. 1/2 - 1 min. on each side, season. Plate up the steaks with the rocket, drizzle with a little lemon juice, serve with the remaining lemon wedges, broccoli and olive vinaigrette.