Preheat the oven to 400 degrees. Line a large baking sheet with parchment paper and set aside.
In a large bowl, combine the shredded chicken, spinach, chiles, sour cream, shredded cheddar cheese, salt and pepper. Stir until well combined.
In a small nonstick skillet, heat about 1 teaspoon of the avocado oil over medium-high heat. Quickly fry 1 tortilla at a time until flexible and easy to roll, about 30 seconds per side. Immediately fill the tortilla with about 2 tablespoons of the chicken mixture and gently roll up. Place seam-side down on he prepared baking sheet. Repeat with the remaining tortillas, adding more oil to the skillet as needed.
Transfer the baking sheet to the oven and bake until the taquitos are crisp and brown on the edges, about 20 minutes. Let cool for 10 minutes before serving, or cool completely to freeze.