Saute onion and garlic in 2 tablespoons oil. Add chilies, tomatoes, 1 teaspoon salt, and oregano. Simmer, uncovered, until thick, about 30 minutes. Set aside.
Combine turkey, sour cream, cheese, and remaining salt, or salt to taste.
Fill tortillas with the turkey mixture, roll, and arrange side by side, seam side down, in a large shallow baking dish, sprayed with cooking spray. Pour sauce over and bake at 350 degrees for 35 minutes, or until heated through. If chilled, add about 15 minutes cooking time. 6 to 8 servings.