1Place the chicken in the slow cooker and cover with water. Add the ginger and some salt, cover and cook on low heat for 4-6 hours.
2Pour the stock through a colander or sieve into a bowl and once it's cool enough to handle, pull any meat off the bones. Return the stock and meat to the pot and add the coconut milk, brown sugar, curry paste, fish sauce, peanut butter, onion, red pepper, mushrooms and cilantro. Stir, cover and let sit for about 15 minutes, or until the veggies have softened and everything has heated through.
3Cut the lime in half and squeeze the juice of half into the soup. Cut the other half into wedges to serve alongside. Serve the soup hot, topped with extra cilantro.