Heat 3 teaspoons of the oil in a large skillet over medium-high heat. Season the steak with ½ teaspoon each salt and pepper.
Cook the steak to desired doneness, 4 to 5 minutes per side for medium-rare. Transfer to a cutting board. Let rest 10 minutes before slicing.
Meanwhile, return the pan to medium heat and add 2 teaspoons of the oil. Season the zucchini with ¼ teaspoon each salt and pepper.
Cook the zucchini, cut-side down, covered, until browned and tender, about 6 minutes. Cut crosswise into ½-inch pieces and divide among plates.
In a bowl, combine the lemon zest, garlic, herbs, bread crumbs, and remaining oil. Sprinkle the mixture over the zucchini and serve with the steak.