1/2 teaspoon freshly cracked pepper (Kampot Whole Black Peppercorns suggested)
1 tablespoon chopped garlic (2-3 cloves)
1 teaspoon coarse kosher salt
2 large sprigs rosemary
1 tablespoon olive oil (for grilling) or 2 tablespoons butter (for pan roasting)
1/2 teaspoon sea salt (Murray River Pink Sea Salt suggested)
Zest and juice lemon, reserving zest for later. Combine the lemon juice, garlic, kosher salt and pepper. Coat porterhouse steak evenly then place in large zipper-locking plastic bag with rosemary. Make sure to press out all of the air or wrap tightly in plastic. Refrigerate for at least 2 hours, overnight is suggested.
Follow the instructions below for your preferred cooking method.
Once steak is cooked, transfer to a clean cutting board. Combine reserved lemon zest with the sea salt.
Carve steak by running knife along the bone to remove both the strip and tenderloin. Slice each steak in 1/4 to 1/2-inch thick slices and serve on a platter. Garnish with lemon and sea salt.
Preheat grill to warm (250°F)
Wrap porterhouse in foil, place on grill away from direct heat and cook slowly for 60-90 minutes, flipping once (internal temperature target should be 100°F). Remove steak from grill and increase grill heat to high (450°F-500°F). Allow steak to rest 15 minutes in foil while grill is heating to higher temperature.
Remove steak from foil, pat dry then brush with olive oil and sear 2-3 minutes per side for medium rare (125°F-130°F). Transfer to a clean cutting board.
Preheat oven to 275°F
Melt 2 tablespoons of butter (or drizzle olive oil) in a pan over medium-high heat. Cook steak for 3 1/2 minutes then flip in pan and cook for another 3 1/2 minutes.
Place steak on baking sheet and put in oven until internal temperature is 130°F for medium rare. Transfer to a clean cutting board.