Sauté turkey and onion in oil. Add oregano, chili powder, salt, paprika and garlic powder.
Cook, uncovered, stirring occasionally until moisture has evaporated. Heat taco shells in 350º F (180 ºC) oven for 5 minutes.
Spoon turkey mixture into taco shells and top as desired with diced tomatoes, shredded lettuce, shredded cheese and salsa.
Notes
Variation: substitute turkey strips and flour tortillas for quick turkey fajitas. You could also serve chopped green onion, black olives, green chilies and avocado as toppings.