With oven rack in middle position, preheat oven to 325°F. Dissolve 5 tablespoons salt in 2 quarts water. Transfer 1 cup of mixture to small bowl. Stir in seeds. Let stand for 5 minutes. Submerge salmon filets in remaining salt/water mixture. Let stand for 15 minutes. Drain seeds. Place in large non-stick skillet. Cook over medium heat, stirring constantly, 2 to 4 minutes, or until golden brown. Remove seeds to plate. Set aside. Wipe out skillet. Remove filets from salt/water mixture. Pat dry. Place white part of green onion and lemon on cutting board. Chop until finely minced and well combined. Put into small bowl. Add lemon juice, tahini, ginger, cayenne, and remaining ⅛ teaspoon salt, stirring to combine. Spread half of lemon mixture over skinned sides of filets. Coat with half of seeds. Turn filets. Cover tops with lemon mixture. Coat with remaining seeds. Heat oil in skillet over medium heat until shimmering. Add filets, skinned side up. Reduce heat to medium-low. Cook 1 to 2 minutes, or until seeds begin to brown. Remove skillet from heat. Carefully flip filets over. Put skillet in oven. Bake 10 to 15 minutes, or until center of fish reaches 125°F. Place on serving platter. Let rest for 5 minutes. Sprinkle with green onion slices. Serves 4.