Using a food processor or box grater, shred the red onion and zucchini.
Finely chop the spinach and parsley.
Place the ground chicken, red onion, zucchini, spinach, and parsley into a medium sized bowl. Add the seasonings, then mix by hand to combine evenly.
In a large cast iron skillet, heat the avocado oil over medium heat.
Once hot, use a portion control scoop or large spoon to scoop approximately 1 ounce portions of mixture. Place into the hot skillet, pressing slightly to form small, level patties.
Cover and cook for 4-5 minutes, or until nicely browned on bottom. Flip and continue cooking for 4-5 minutes, or until completely cooked through.