Lightly coat a medium saucepan with cooking spray. Heat saucepan over medium heat. Add onion; cook and stir until onion is tender. Stir in pork, frozen corn, salsa, and green chili peppers.
Cover and cook over medium-low heat about 10 minutes or until heated through, stirring occasionally. Spoon pork mixture into taco shells. If desired, top with tomatoes, lettuce, and/or cheese. Makes 4 (2-taco) servings.