Cut head of garlic in half, place on a square of foil, and drizzle with olive oil. Wrap. Bake at 400 degrees F (200 degrees C) for 45 minutes. Squeeze roasted garlic cloves out of skins, and mash into a puree. Set aside.
Sprinkle steak with salt and a generous amount of freshly ground pepper. Heat a large heavy skillet over medium high heat, but do not add fat. When hot, cook seasoned steak until seared and well browned on both sides, about a minute per side. Reduce heat to medium, and add 2 tablespoons of the butter. Continue to cook for 3 to 5 minutes on each side. Remove meat, and keep warm.
Pour off the fat in the skillet, and add the scallions and red wine. Bring to a boil, and whisk in the garlic puree. Boil until the wine is reduced by half, and is thick and syrupy. As it boils, scrape up browned bits with a wooden spoon. Stir in the meat juices that have accumulated under the steak. Boil for another second or so. Remove from the heat, and stir in the remaining 2 tablespoons of butter until it is incorporated into the wine sauce.
Quickly slice the meat against the grain, into thin strips. Arrange on a hot platter, and pour the sauce down the center of the slices. Serve at once.