Preheat the oven to 375 degrees. Swirl 1 tsp oil in a skillet and add the turkey, half of the onions, half of the garlic, and 1/4 tsp. of the salt. Cook til brown.
Meanwhile, heat a saucepan and swirl in the remaining tsp. oil. onions, garlic 1/4 tsp salt, oregano, and cumin. Cook about 8 min. Stir in the enchilada sauce, chiles, and vinegar; bring to a boil. Simmer 10 minutes. Remove from heat and stir in the cilantro.
Arrange one-third of the tortilla halves in an overlapping layer on the bottom of a 7 x 11 inch baking dish. Spoon one third of the turkey mixture over the top; top with 1/3 of the sauce and sprinkle with 1/3 of the cheddar. Repeat the layering twice. Cover and bake 20 min.. Remove cover and bake 5 minutes more.