Place chicken, sweet potatoes, ginger and garlic in bottom of slow cooker. In a bowl, whisk stock and peanut butter until blended. Stir in tomatoes, coriander, 1/2 tsp of the salt and the black pepper. Pour into slow cooker. Press down until chicken and potatoes are mostly submerged. Cover and cook on HIGH for 4 hours or LOW for 6 hours.
Carefully remove chicken to a cutting board. Shred chicken, discarding bones. Stir vinegar and remaining 1/4 tsp salt into liquid. Stir in shredded chicken.
Ladle into bowls and garnish with cilantro and peanuts, if using.