Preheat a 2-burner cast-iron grill or two grill pans over medium-high heat for about 3 minutes.
Drizzle the grapeseed oil over the steaks and sprinkle with salt. Place the steaks on the grill, seasoned-side down, and cook for 4 to 5 minutes per side, or to the desired doneness.
Place the broccoli spears on the grill next to the steaks and cook for 4 minutes per side. Brush the steaks with some teriyaki glaze just before taking them off the grill. Let the steaks rest for about 8 minutes before slicing.
Arrange the sliced steak and grilled broccoli on a serving platter and finish with additional teriyaki glaze. Sprinkle with toasted sesame seeds and garnish with several sprigs of cilantro.
Hawaiian-Style Teriyaki Glaze:
Combine the pineapple juice, soy sauce, scallions, brown sugar, ginger, garlic and sesame oil in a medium saucepan. Bring to a boil, then reduce the heat to a simmer. Cook until thick, about 20 minutes.