Prepare the lamb: Take the lamb striploin out of the fridge for about 30 minutes before cooking to bring it to room temperature.  

Using a sharp knife lightly score the fat cap about halfway through at an angle every ¼ inch.  Then repeat at an angle creating a cross hatch of “diamond” design. (This will help the fat render more evenly and slightly quicker).

Heat the pan: Place a cast iron skillet or heavy-bottomed pan over medium-low heat. 

Sear the lamb: Place the lamb striploin in the hot pan, fat-side down first, and sear for 10-15 minutes, until the fat is rendered, and the outside is golden brown. Turn up the heat to medium high, flip and sear the other side for another 3-4 minutes. 

Add aromatics: add smashed garlic, fresh herbs, and butter(optional). Tilt the pan slightly and spoon the fat and herbs over the lamb to baste it. Do this for about 2-3 minutes. 

Check doneness: For medium-rare, cook until the internal temperature reaches about 130°F (54°C). If you prefer more doneness, cook a little longer. 

Rest the lamb: Remove the lamb from the pan and let it rest for 5-10 minutes before slicing. This allows the juices to redistribute. 

Slice and serve: Cut into ¼ to ½ inch slices and enjoy!