Add the diced onion, minced garlic, and grated ginger to the slow cooker.
Place the chicken pieces on top of the aromatics.
Stir in the Thai red curry paste until the chicken is lightly coated.
Add the cubed sweet potatoes and sliced red bell pepper.
Pour in the chicken broth and coconut milk. Stir gently to combine.
Season with salt and black pepper.
Cover and cook on low for 7 to 8 hours or on high for 4 hours until the chicken is tender and the sweet potatoes are soft.
Stir in the lime juice just before serving.
Ladle into bowls and top with fresh cilantro.