In a medium bowl, combine the softened butter, pickled ginger, chives, lime juice, and a pinch of salt. Mix until well combined. Place the mixture onto a piece of plastic wrap and shape it into a log. Roll it tightly and refrigerate until firm, about 30 minutes.

Pat the porterhouse steaks dry with paper towels and season generously with salt and black pepper on both sides. In a small bowl, mix together the nigella seeds and lime zest. Press the mixture onto both sides of the steaks, ensuring an even coating.

Heat the olive oil in a large skillet over medium-high heat until shimmering. Carefully add the steaks to the skillet and sear for about 4-5 minutes on each side for medium-rare, or until they reach your desired level of doneness. Use a meat thermometer for accuracy; aim for 130°F (54°C) for medium-rare.

Transfer the steaks to a cutting board and let them rest for about 5-10 minutes. This allows the juices to redistribute and ensures a juicy steak.

Slice the steaks against the grain and serve with slices of the pickled ginger-chive compound butter on top. Enjoy with your favorite sides!