How to Make It
Heat a large cast-iron skillet over medium-high. Season steak with 1 teaspoon each salt and pepper, gently pressing on both sides of steak to adhere. Heat 1 tablespoon oil in skillet. Add steak and cook, undisturbed, for 4 minutes. Flip and cook, undisturbed, until seared on other side, 4 to 5 minutes. Add 1 tablespoon oil to skillet and continue cooking steak, spooning oil drippings over steak often, until desired degree of doneness, 2 to 3 minutes for medium-rare (a thermometer inserted in thickest portion will register 122°F). Transfer to a plate; let rest for 10 minutes before slicing against the grain.
Meanwhile, whisk vinegar, honey, and remaining ¼ teaspoon each salt and pepper and 3 tablespoons oil in a large bowl. Stir in blackberries. Add arugula and pistachios and toss to coat. Top with steak and cheese.