Remove the cutlets from the refrigerator 1 hour before cooking. To make the marinade, put the garlic, lemongrass, ginger and sea salt in a mortar and pound into a rough paste with the pestle. Add the herbs and pound for a further minute, then stir in the extra virgin olive oil and mix together well.
Mix the cutlets with the marinade and leave for at least 1 hour to infuse. Preheat the barbecue and make sure the grill bars are clean. When hot, put the cutlets on the hottest part. Cook for about 2 minutes on each side for medium rare.
Put on a plate and cover with foil. Rest in a warm place for 10 minutes. To serve, place 3 cutlets on each of four plates. Mix a little oil with the juices on the resting plate and pour over the cutlets. Give a good grind of fresh pepper, place a lemon wedge on each plate and serve immediately.