In a medium bowl, combine the softened butter, white miso paste, minced ginger, soy sauce, rice vinegar, and sesame oil. Mix well until all ingredients are fully incorporated.

Place the butter mixture onto a piece of plastic wrap and roll it into a log shape. Twist the ends to seal. Refrigerate until firm, at least 30 minutes.

Preheat your grill or stovetop skillet over medium-high heat.

Rub the hanger steak with olive oil and season generously with salt and pepper on both sides.

Press the toasted sesame seeds and chopped scallions onto both sides of the steak, making sure they adhere well.

Place the crusted steak on the grill or skillet. Cook for about 4-5 minutes on each side for medium-rare, or until your desired doneness is reached.

Remove the steak from the heat and let it rest for 5 minutes.

Slice the hanger steak against the grain into thick slices. Place on a serving platter and top with slices of the ginger-miso compound butter. Garnish with additional fresh scallions if desired.