Cut the dried shiitake mushrooms in half with kitchen scissors. Add the shiitake mushrooms and 1 cup of boiling water into a bowl. Cover and let it sit for 20 mins. (You will need to reserve some of the mushroom soaking liquid so don't throw it out.)
Add all the sauce ingredients into a bowl and whisk until combined.
Cut the chicken thighs into roughly 1.5 cm thick strips and place in a bowl. Add 2 tbsp of the sauce to the chicken and allow to marinate for 20 mins.
Prep all other vegetables.
Take the mushrooms out, and reserve 3 tbs of the soaking liquid. Squeeze the water out of the mushrooms into the sink, then remove the stalk and thinly slice.
In a small bowl, add the 3 tbsp of reserved mushroom soaking liquid and the cornstarch. Using your finger or a teaspoon, mix them together until fully combined.
Add 1/2 cup of water and the cornstarch mixture to the sauce and whisk.
Submerge the hokkien noodles with boiling water in a large bowl. Loosen up the noodles with some tongs then drain.
Place a large empty bowl next to your stove top and heat a non-stick wok / fry pan to high.
When the wok / pan is hot, add 1 tbsp of oil and the chicken. Cook for 5 mins or until done (Note 2). Put the cooked chicken into the bowl.
Add 1 tbsp of oil and add the onions, garlic and ginger. Cook for 30 seconds.
Add the shiitake mushrooms and the capsicum. Cook for 1 minute.
Add the choy sum, snow peas and the sauce. Stir and cook for 1 minute.
Take out the ginger slices and turn the heat to low. Add the chicken and hokkien noodles to the wok / pan and combine well.
Garnish with chopped coriander and spring onion, and serve with sriracha/chilli sauce.