Take the Porterhouse steak out of the refrigerator and let it come to room temperature for about 30-45 minutes.

Preheat your grill or cast-iron skillet over high heat.

In a mixing bowl, combine the chopped spring onions, grapefruit zest, olive oil, salt, and black pepper. Mix well to form a paste.

Pat the steak dry with paper towels. Season generously with salt and black pepper on both sides.

Place the steak on the hot grill or skillet. Sear for 4-5 minutes on one side until a crust forms.

Flip the steak and immediately spread the spring onion and grapefruit mixture over the top.

Continue cooking for another 4-5 minutes on the second side for medium-rare, or until it reaches your desired doneness (use a meat thermometer for precision; 130°F for medium-rare).

Once cooked, remove the steak from the heat and let it rest for at least 10 minutes to allow the juices to redistribute.

In a small bowl, combine the softened butter, crushed black peppercorns, and bourbon. Mix until well combined.

Slice the steak against the grain and top with a generous dollop of black peppercorn-bourbon butter. Garnish with fresh herbs. Serve immediately with your choice of sides.