Cook the rice noodles and set aside.
Finely slice the onion. Drain the tofu (if necessary), pat it dry with some kitchen paper and chop it into bite-sized pieces.
.Heat the cooking oil in a wok or pan, and gently stir-fry the tofu and shallot for 2 minutes. Add the vegetables and gently stir fry until they are cooked how you like.
Add the noodles and stir in the tamarind/pad thai sauce and coat the noodles and veg.
Trim the spring onions. Chop the white part, and set it to one side. Cut the green part into short lengths.
When the noodle and veg mixture is almost dry, stir in some of the beansprouts and the green parts of the spring onions. Stir everything together quickly and then remove from the heat.
Pile the pad Thai on to a serving dish. Garnish the edge of the plate with the chopped white parts of the spring onions, chilli powder, fine slices of lime and ground roasted peanuts.