Steam or bake your chicken pieces and allow to cool. To steam the chicken in the instant pot. Place the steaming rack in the bowl of the Instant Pot. Salt the chicken and place on the rack. Pour over a cup of chicken broth. Place the lid on and make sure the valve is in the sealed position. Set the Instant Pot to manual high pressure for 15 minutes and then quick release. When the valve has dropped open, remove the chicken. Allow to cool before cutting it into smaller pieces.
Boil noodles according to the packet instructions. Drain and set aside.
Chop the pak choy, separating the white hard ends and the soft leafy green tops.
In a large pot, add 1 tbsp olive oil and heat. Add spring onion and the white hard ends of the pak choi and sauté until soft, 2 minutes.
Add the garlic and fresh ginger and cook for another minute.
Add mushrooms and sauté until soft, 5 minutes
Add broccolini and sauté for another 5 minutes
Add broth and bring to a boil. Once boiling, add in chicken pieces and green parts of the pak choi. Cook until the broccolini and pak choi are tender, 10-15 minutes.
Divide noodles between bowls and pour over broth mix.