Preheat oven to 375 degrees F. Lightly oil a 9 x 13 baking dish or coat with nonstick spray.
Heat canola oil in a large cast iron skillet over medium heat. Add onion, and cook, stirring frequently, until translucent, about 2-3 minutes. Stir in garlic, oregano and cumin until fragrant, about 1 minute. Remove from heat; stir in green chiles.
In a large bowl, combine green chile mixture, chicken, 1/3 cup salsa verde and cilantro. Stir in 1 1/2 cups cheese; season with salt and pepper, to taste.
To assemble the enchiladas, lay tortilla on a flat surface and spoon 1/2-3/4 cups of the chicken mixture in the center. Roll the tortilla and place seam side down onto prepared baking dish. Repeat with remaining tortillas and chicken mixture. Top with remaining salsa verde and remaining 1 1/2 cups cheese.
Place into oven and bake until bubbly, about 35-40 minutes.
Serve immediately, topped with dollops of sour cream.
Notes
Soften the tortillas. Warm the tortillas first so they are easier to roll. Wrap the tortillas in a damp paper towel and microwave for about 30 seconds. You can also fry the tortillas, in batches, in a little bit of oil (about 1 tablespoon vegetable oil) until crispy but pliable.
Use the right cheese. Use melting cheeses such as Monterey Jack, Oaxaca, or Chihuahua.
Do not overstuff. Size matters! Overstuffing may sound like a good idea since the filling is the best part, but this can result in ripped tortilla and overspill.
Avoid a soggy bottom. Nobody likes soggy enchiladas! Be sure to pour the sauce on top, adding the filled enchiladas to the pan first.