Combine first 7 ingredients in a medium bowl; set aside.
Sprinkle 1/4 teaspoon salt over swordfish. Heat oil in a large nonstick skillet coated with cooking spray over medium-high heat until hot. Add swordfish; cook 4 minutes on each side or until swordfish flakes easily when tested with a fork. Remove swordfish from skillet; set aside, and keep warm.
Recoat skillet with cooking spray; place over medium-high heat until hot. Add sliced onion; sauté 4 minutes or until lightly browned. Add tomato mixture; bring to a boil. Cover, reduce heat, and simmer 5 minutes.
Return swordfish steaks to skillet, nestling them in tomato mixture. Cover and simmer 1 to 2 minutes or until sauce thickens. Place 1/2 cup cooked linguine on plate; top with swordfish and 1/2 cup sauce.