Heat a skillet over medium heat and add the ground turkey. Cook it while breaking it up with a spoon until it is no longer pink, about 5 minutes. Add the diced onion and minced garlic and cook for another 2 minutes until the onion starts to soften.
Transfer the turkey mixture to the slow cooker. Add the cubed sweet potatoes, black beans, fire-roasted tomatoes, minced chipotle peppers, chicken broth, chili powder, cumin, salt, and black pepper.
Stir everything together until the spices are evenly distributed. Cover and cook on low for 6 to 7 hours or on high for 3 to 4 hours, until the sweet potatoes are fork-tender.
Taste and adjust salt or pepper if needed. Ladle the chili into bowls and top with chopped fresh cilantro before serving.