Put the rice noodle nests in a large bowl and cover with boiling water from a kettle. Leave to stand.
Put all the base ingredients in a blender and whizz until you have a lovely yellow, creamy base and set aside.
Heat a little olive oil in a large frying pan (skillet) and fry the sliced onion and mushrooms for about 5 minutes until nice and soft. Add the base cream to the pan an