Put the noodles in a bowl, cover with boiling water and leave to soften for about 5 minutes or according to the packet instructions (the time needed for soaking will depend on the thickness of the noodles you use). Drain in a colander, rinse under cold water and set aside.
Heat the oil in a saucepan over a medium heat. Add the red pepper and mushrooms, and cook for 3–4 minutes until softened. Add the laksa or curry paste and cook, stirring, for 1 minute until fragrant.
Pour in the stock and coconut milk, and bring to the boil. Reduce the heat and simmer for 5 minutes.
Add the prawns, spring onions, drained noodles and coriander, stir to mix and cook for 3–4 minutes until the prawns have turned pink and are just cooked through. Serve immediately.