Mix together all the ingredients for the compound butter in a small bowl and set aside.
Season the swordfish to taste with sea salt. Heat a glug of olive oil in an ovenproof pan over medium-high heat, then fry the swordfish on one side until golden brown (shouldn't be more than 2 minutes).
Turn the swordfish over and move the pan to the preheated oven. Roast for 5-10 minutes (this really depends on the thickness of your steaks and how well cooked you like your swordfish). Rather err on the side of undercooking slightly - overcooked swordfish will be dry!
Transfer the fish to a serving dish. Add the butter mix to the pan, just until it melts. Spoon the sauce over the fish and serve immediately. I served it with creamy cauliflower mash and roasted Mediterranean veg - it was a fantastic combination.