2.
Pat your fish dry and then make a few cuts across the skin
3.
Season with salt and pepper, rubbing it all over, including in the slits and the cavity
4.
Add the onions and lemon slices in the cavity, slits and around the fish
5.
Place in the oven for about 20minutes, you may want to broil/grill for the last few minutes to get a crispy skin
6.
Meanwhile, mix together the dressing ingredients
7.
Place the rocket on the plate, add your fish and then drizzle with your dressing