Combine all the dressing ingredients, stirring well to dissolve the sugar.
Slice the eggplant into 1 cm slices. Line a large baking tray with aluminium foil.
Brush the eggplant with the dressing on both sides. Cook under the grill (broiler) for about 10 minutes, basting often and turning when golden. Remove, cut into halves or thirds and toss with the remaining dressing.
In the mean time, cook the noodles according to packet instructions. Drain, rinse and drain well.
Toss the noodles, green spring onions and sesame with the eggplant. Garnish with green onion and sliced red chilli if desired.