Step 1

Whisk scallions, pear, dark soy sauce, sesame oil, 1 tablespoon mirin, 1 tablespoon brown sugar, garlic, lime juice, ginger, black pepper, and red pepper flakes together in a bowl; pour into a resealable plastic bag. Add beef; coat with the marinade, squeeze out excess air, and seal the bag. Marinate in the refrigerator, 8 hours to overnight.

Step 2

Preheat an outdoor grill for medium-high heat and lightly oil the grate.

Step 3

Transfer beef slices from marinade to preheated grill, reserving marinade; cook until no longer pink in the center, about 3 minutes per side. Place beef in a serving dish.

Step 4

Place marinade in a saucepan with soy sauce, water, gochujang, 1 teaspoon brown sugar, and 1 teaspoon mirin. Bring to a boil and cook until thickened to sauce consistency, 3 to 5 minutes. Pour sauce over beef.