Combine 5 tablespoons teriyaki sauce and fish in a zip-top plastic bag. Seal and marinate 20 minutes. Toast sesame seeds in a large nonstick skillet over medium heat, and set aside. Drain fish, discarding marinade. Add fish to skillet, and cook 5 minutes. Turn and cook for 5 more minutes over medium-low heat. Remove from skillet, and keep warm. Add the zucchini, scallions, and 2 teaspoons oil to skillet. Sauté 4 minutes, or until lightly browned. Stir in 2 tablespoons teriyaki sauce. Sprinkle with sesame seeds, and serve with salmon.