Place whole chicken in a large pot and cover with the water. Add salt, carrot, ginger, spring onion, peppercorns, kaffir lime leaves and lemongrass. Cover and bring to the boil. Reduce heat and simmer, partially covered, for around 1 hour or until chicken is just cooked. Remove chicken and set aside to cool slightly. Strain the stock through a fine sieve and set aside.
When the chicken is cool enough to handle, pull off the white parts of chicken meat (you want about 2 cups’ worth) and shred with your fingers, then finely chop. Put in a bowl along with second measure of ginger and coriander or chives. Mix to combine.
To make the dumplings, take a wonton or dumpling wrapper and place on a flat surface. Add 1 Tbsp of chicken mixture to the middle. Dip your finger into a small bowl of water, then wet around the edge of the wrapper. If you are using a round-shaped dumpling wrapper, fold the circle in half to make a half-moon shape and press the edges firmly to seal. If using a square-shaped wonton wrapper, gather the sides and pull into the middle with a twist so it resembles a little money bag. Set aside.
Add the strained chicken stock back to the pot and add soy sauce and sesame oil. Bring to a simmer and add bok choy and dumplings. Cook for a couple of minutes – the soup is ready when the dumplings rise to the surface.
Divide broth and dumplings between bowls. Garnish with reserved spring onion or chives and serve with a dish of sweet chilli or chilli sauce for dipping.