1. Blanch and drain the green beans.
2. Place the beans back in the pot they were cooked in and add the red onion and cannellini beans and 30ml of olive oil.
3. Brush the bream with oil, score the skin, season and place under a hot grill, cook until the skin crisps then turn and cook the flesh side for approx. 1 minute.
4. Heat the bean mixture, season with salt and pepper and sqeeze in the juice of a lemon, throw in the rocket at the last minute.
5. Spoon a little of the bean mixture on to the plate, then the bream and top with remaining beans.