How to Make It
Combine pear, soy sauce, sesame oil, brown sugar, ginger, garlic, and 2 of the sliced scallions in a food processor; pulse until finely chopped, about 15 times. Reserve 1/4 cup of the marinade mixture in a small bowl.
Combine sliced steak, remaining marinade mixture, and 1/4 teaspoon of the crushed red pepper in a medium bowl. Cover and chill 2 hours.
Heat 1 tablespoon of the oil in a large cast-iron skillet over high. Using tongs, transfer half of the steak from marinade to hot oil in skillet; cook, stirring often, until steak is cooked through and edges are crisp. Transfer to a serving platter. Repeat with remaining 1 tablespoon oil and remaing steak. Drizzle reserved marinade mixture over steak. Sprinkle steak with salt, sesame seeds, and remaining 2 sliced scallions and 1/4 teaspoon red pepper. Serve with rice, cucumbers, kimchi, and butter lettuce leaves.