Defat the Pork fillet and grease it with oil. In a mixing bowl prepare an aromatic mix of salt, pepper and rosemary. Spread the mix evenly over the previously greased pork fillet. Brown both sides of the Pork fillet on the gas barbecue for around 2 minutes each side. Once browned, move the Pork fillet onto the barbecue for indirect cooking. Cook the pork fillet until the temperature in the middle is 68/72 °C (154/161 °F). Meanwhile prepare the sauce. Gently melt the butter together with the peel of an orange. Once melted, remove from the heat, add the juice of one orange, the mixed flower honey and add salt and pepper to taste. Cut the fillet crosswise and serve it with orange sauce. Serve piping hot.