Heat 3/4 tsp oil in a medium nonstick skillet over medium-high heat. Add turkey; sauté 1 minute. Add 3/4 tsp oregano, salt, 1/4 tsp cumin, pepper, and 2 cloves garlic; sauté 1 minute. Add 1/2 cup corn and onions,and sauté 1 minute.
Spoon into a bowl; stir in chopped cilantro and set aside.
Heat 1 1/2 tsps oil in skillet over medium heat. Add 1/4 tsp oregano, remaining 1/2 tsp cumin, and 1 clove garlic; saute 1 minute.
Add flour, chili powder, and cinnamon; cook, stirring constantly with a wire whisk; 1 minute.
Gradually add water and broth to mixture, and cook, stirring constantly with whisk, 5 minutes or until mixture is thickened and bubbly. Pour sauce into a bowl; cover and set aside.
Brush remaining 1 tsp oil evenly over both sides of tortilla halves. Place a nonstick skillet over medium high heat until hot. Add 5 tortilla halves, and cook 30 seconds on each side or until softened. Remove from skillet; set aside and keep warm. Repeat procedure with remaining tortilla halves.
Arrange 5 tortilla halves in an 8 inch square baking dish coated with cooking spray. Spread 1/3 cup sauce over tortillas, and top with turkey mixture. Spoon 2/3 cup sauce over turkey mixture; top with remaining 5 tortilla halves. Spread remaining 2/3 cup sauce over tortillas; top with cheese and remaining 1/4 cup corn.
Bake at 450°F for 15 minutes or until bubbly. Cut into squares; serve with sour cream. If desired garnish with cilantro sprigs and tomato.