Preheat your oven to 400°F (200°C). Place the bone marrow in a baking dish and roast for about 15-20 minutes, or until the marrow is soft and slightly browned.

In a bowl, combine the softened butter, roasted bone marrow, smoked paprika, garlic powder, cayenne pepper, and a pinch of salt. Mix until well combined.

Transfer the mixture onto a piece of parchment paper, shape it into a log, and refrigerate until firm.

In a small bowl, mix together the dried lime powder, chopped cilantro, olive oil, salt, and pepper. Rub this mixture all over the hanger steak, ensuring it is evenly coated. Let it marinate for at least 30 minutes at room temperature, or refrigerate for up to 2 hours for more flavor.

Preheat a grill or a cast-iron skillet over medium-high heat. Remove the steak from the marinade and let any excess marinade drip off.

Grill or sear the steak for about 4-6 minutes on each side for medium-rare, adjusting the time based on your preferred doneness. Once cooked, remove the steak from the heat and let it rest for 5-10 minutes.

Slice the hanger steak against the grain into thick strips. Serve with dollops of the spiced bone marrow butter on top, allowing it to melt over the warm steak. Garnish with chopped parsley and additional cilantro if desired.