Add the lamb, sweet potatoes, onion, garlic, and ginger to the slow cooker.
In a bowl, whisk together the coconut milk, chicken broth, Thai red curry paste, and fish sauce until smooth.
Pour the mixture over the ingredients in the slow cooker and stir to combine.
Cover and cook on low for 8 hours, until the lamb is very tender and the sweet potatoes are soft.
Stir in the lime juice and season with salt and pepper.
Ladle into bowls and top with chopped cilantro before serving.