Combine the cilantro, olive oil, oregano, garlic, lime juice, orange juice, tomatoes, onions, bell peppers, 1 1/2 teaspoons salt, and a few grinds of pepper in a food processor. Pulse until it forms a chunky sauce.
Add the sauce to a slow cooker along with the chicken thighs, and toss together. Cover and cook on low for 5 hours.
After 3 hours, add the sweet potatoes, nestling them underneath the chicken.
About 30 minutes before the stew is done, add the kale.
Serve with hot sauce if desired.
Recipe Adapted from foodnetwork.com/recipes/slow-cooker-citrus-chicken-and-sweet-potato-stew.html, Retrieved February 2015