Coat a large skillet with cooking spray and heat over medium high heat. Add onions and cook until translucent, about 5 minutes.
Add sweet potatoes and cook for 3-4 minutes, until barely tender. Add kale and cook until wilted, about 2-3 minutes.
Set aside.
Add chicken meat to your food processor and process on pulse until ground. Transfer meat to large mixing bowl.
Add the rest of the ingredients and blend until well combined.
Cover with a plastic film and refrigerate for at least 4 hours, or overnight.
Divide your chicken mixture into 4 equal portions and form into patties.
Coat a large non-stick pan with cooking spray and heat over medium high heat. Add patties and cook until a nice golden crust forms, about 4-5 minutes, then flip to the other side, cover and cook until golden again and patties are cooked through, about 5 minutes.
Serve as is, or on a nice whole grain hamburger bun.