1. To make the dressing, purée the garlic,ginger and mirin in a blender,then add the remaining dressing ingredients and blend again.
2. Bring a medium-sized pot of water to the boil and cook the noodles for five minutes,or according to packet instructions. Drain and refresh in iced water for a few minutes. Then drain the noodles again,toss with a little of the dressing and set aside.
3. In another bowl,combine the sesame oil,cucumber,capsicum,bean sprouts,chicken and prawn and toss lightly.
4. If preparing ahead,keep the two elements separate,covered and refrigerated.
5. Immediately before serving,pile the noodles onto a large plate,and spoon the chicken and prawn mixture over the centre. Pour the rest of the dressing over the noodles,and a little over the chicken and prawns,then sprinkle over the shallots and sesame seeds.