In a large, shallow dish, combine the soy sauce with the sugar, white wine, chopped garlic, toasted sesame oil and crushed pepper, stirring to dissolve the sugar. Add the slice flank steak and coat thoroughly in the marinade. Cover and refrigerate the steak for at least 4 hours.

Light a grill or heat a griddle. Rub the scallions all over with the vegetable oil and grill them over high heat, turning once until the scallions are soft about 2 minutes. Season with salt.

Working in batches, grill the steak over high heat until the slices are richly browned and medium rare about 30 seconds per side. Serve with the grilled scallions and rice.