Get the butter out of the fridge and let it come up to room temperature in the package.
Put the steak in the refrigerator for half an hour.
Chop fine the rosemary and thyme leaves and do the same with the garlic.
Take the butter out of the package and put it in a large bowl or tray. Add the rest of the ingredients and knead this until it looks and tastes like herbed butter.
Take the steak out of the fridge and press lumps of butter on the steak. Build a layer all around until you no longer see naked meat. Put the steak, uncovered in the fridge for a week.
After seven days, take the steak out of the fridge and cut away the butter without cutting into the meat. Take your time.
Cut off all the discoloration to reveal the dark red meat underneath.
Fire up your grill to an indirect temperature of 120°C (248F). Put a thermometer in the meat and let the steak cook to a core temperature of 52°C/126°F.
Take the steak out and let it rest while you let the grill heat up until the grates are piping hot. Let some of the herbed butter that you cut off the steak melt.
Sear off the steak for a good crust. Then you cut it into thin slices and pour over the melted butter.