Place the miso paste, water, chilli, garlic, bay leaf and ginger into a saucepan, bring to the boil and stir to combine.
Add the noodles to the pan and simmer for 2-3 minutes, or until softened.
Add the pak choi leaves to the pan and cook for 1-2 minutes.
To serve, pour the soup into a serving bowl and garnish with fresh coriander.
