Preheat oven to 200 C.
Cook the noodles as per packet instructions. Run them under cold water. This stops them from getting gluggy and sticky.
Chop the broccoli florets into bite-sized pieces. Chop the stems and smaller stalks into roughly the same size as the florets. Slice the mushrooms lengthwise into thin slivers. If the stems are fresh, leave them on.
Toss the broccoli and mushrooms with toasted sesame oil or regular vegetable oil. Lay them out on a baking tray and roast for 20 mins.
For the sauce: mix all the ingredients listed above. Taste and adjust seasoning. (Start with 1 tbsp of chilli oil and add more if necessary.)
Heat the oil in a large wok or pot. Sauté slivered onions and garlic until the onions start to brown around the edges.
Add the sauce and the roasted vegetables. Swill out the sauce bowl with ¼ cup of water and add to the pot. Tip the noodles in and toss through. Check seasoning. Add more of one or more of the sauce ingredients to get the right flavour and consistency you want.
Add spring onion tops and broccoli leaves over the top. Drizzle over a bit more sesame oil and chilli oil to finish. Serve hot. Also reheats very well.