Heat broiler. Place the steak on a broilerproof baking sheet and season with ½ teaspoon each salt and pepper.
Broil to the desired doneness, 4 to 5 minutes per side for medium-rare. Let rest at least 5 minutes before slicing.
Heat the oil, pine nuts, and garlic in a large skillet over medium-high heat. Cook, stirring, until the mixture is golden, 1 to 2 minutes.
Add the squash, bell pepper, crushed red pepper, and ½ teaspoon salt and cook, stirring often, until the vegetables are tender, 4 to 5 minutes.
Sprinkle the vegetables with the chives. Serve with the steak.
