Chicken yaki soba is a super quick Asian dish to make and the sauce can be prepared ahead of time and kept in the refrigerator.
First cook the noodles in a large pan of boiling water for 2-3 minutes until just tender. Drain and refresh under cold running water before setting aside.
Put the yaki soba sauce, beansprouts and prawns in a large bowl. Mix in the noodles. Set aside.
Heat a wok over a medium heat for 1-2 minutes or until almost smoking and add the oil. Add the onion (both kinds), chicken, peppers and courgette and stir fry for 5 minutes until the chicken is cooked through; it is important that the chicken is cut into thin strips or it won;t cook through properly.
Add the noodles etc to the wok and stir fry quickly for 3 minutes until warmed through.
Move everything to one side of the wok and pour the egg into the space. With a wooden spatula move it around and up the side of the wok so that it cooks quickly. Once just cooked, mix it through with everything else in the wok.
Serve garnished with the sesame seeds.
(If you have pickled ginger, this also makes a good garnish)