Season the swordfish steaks with salt and pepper.
Dice or quarter the tomatoes and transfer them to a bowl with all the juices. Remove the stones from the olives and chop the flesh if the pieces are still large. Stir them into the tomatoes with parsley, season to taste and set aside.
Cook the couscous according to the instructions on the packet and set aside.
Meanwhile, cook the swordfish steaks, 2 at a time, in a preheated hot griddle pan. Cook on the first side for 4 minutes, without disturbing them, then turn and cook for a further minute.
Serve the swordfish and couscous immediately, topped with the olive and tomato salsa and accompanied with a green salad, if liked.