Strip all the rosemary needles and peel the garlic cloves
If you have a small blender or food processor, you can blend the garlic, rosemary and balsamic together, then add in the olive oil to make a herb flecked mixture. If not, chop the rosemary and garlic finely, then use a pestle and mortar to pulverise before adding in the balsamic and finally whisking the mixture together with the oil.
Put the steak in a plastic or ceramic dish. Coat the steak well on both sides and pour the remaining marinade over. Cover and leave at room temperature for an hour or in the fridge for up to 8 hours (remember to remove from the fridge half an hour before you want to eat!)
Heat a griddle till smoking hot.
Wash the rocket and drain well. Dress with the vinaigrette then plate up, adding the parmesan shavings
Gently scrape any extra marinade off the steak with a spoon or round ended knife. Season well with salt and pepper.
Cook the steak according to taste and depending on the thickness of your cut. My sirloin of about 1cm thickness took less than 2 minutes on each size to produce a rare steak.
Put the steak onto the plate of rocket and drizzle any meat juices from the pan over the meat.