1.Quarter capsicums; remove and discard seeds and membranes. Grill capsicum, skin-side up, until skin blisters and blackens. Cover capsicum quarters in plastic or paper 5 minutes. Peel away skin; cut each quarter in half lengthways. Cut pieces into thick diagonal slices. (Can be made 1 day ahead to this stage and refrigerated, covered.)
2.Meanwhile, cook noodles in large saucepan of boiling water, uncovered, until just tender; drain.
3.Boil, steam or microwave beans until just tender; drain.
4.Make the sesame-soy dressing. Combine ingredients in screw-top jar; shake well.
5.Gently toss capsicum, noodles, beans, onion, seeds and coriander in large bowl with sesame-soy dressing.