Pat the chicken thighs dry with paper towels.
In a small bowl, whisk together the salt, garlic powder, onion powder, Italian seasoning, smoked paprika, and black pepper.
Season both sides of the chicken thighs evenly with the spice mixture.
Heat the avocado oil in a large heavy-duty cast iron skillet over medium-high heat until shimmering.
Place the thighs skin-side down and sear undisturbed for 5 minutes to render fat and crisp the skin.
Reduce heat to medium-low and continue cooking the skin-side down, undisturbed, for 20 minutes until the skin is golden brown and very crispy.
Flip the thighs and cook for an additional 10 minutes, or until an instant-read thermometer inserted into the thickest part registers 170°F (77°C).
Remove from the skillet and let rest a few minutes before serving.