Cut chicken thighs into bite-size chunks (about 1 inch) and place them in a large bowl. Add half of the avocado oil, cornstarch, salt, and pepper. Mix to evenly coat and set aside.
Heat up the oil in a large skillet over medium heat for 2 minutes. Add the chicken and cook each side until golden brown but not completely cooked through (about 4-5 minutes). Do not crowd the pan, you may need to cook in batches.
Transfer to a bowl or plate with a slotted spoon and set aside.
Add the diced onion to the pan and cook for 2-3 minutes or until soft. Add the minced garlic and 1 tablespoon of oil from the sun dried tomatoes (the remaining oil from the sun dried tomatoes can be drained). Cook for 1 minute, stirring often.
Add broth to the pan, scraping from the bottom and stirring frequently. Cook until broth has reduced down by at least half.
Add sun-dried tomatoes to the skillet. Fry for 2-3 minutes until well combined, stirring occasionally.
Add coconut milk and nutritional yeast to the skillet. Once the coconut milk has reached a boil, turn the heat down to medium-low. Add spinach to the pan and stir until slightly wilted, about 1 minute.
Add chicken back into the pan and sprinkle with Italian seasoning. Stir frequently for another 7-10 minutes, allowing the chicken to cook all the way through.
Season with additional salt and pepper if necessary.