Heat a nonstick frying pan over a medium-low heat and dry-fry the sesame seeds for 2 minutes, stirring frequently, until golden brown and toasted.
Set aside.
Cook the rice noodles according to the packet instructions, then refresh under cold running water.
Segment the oranges over a bowl to catch the juice.
Transfer the noodles to a large bowl, add the orange segments, prawns, watercress and onion and mix together.
Add the sweet chilli sauce and lime juice to the orange juice and whisk together.
Pour over the noodle mixture and toss together.
Arrange the lettuce leaves on a large serving plate or 4 individual plates and top with the noodle salad.
Sprinkle with the toasted sesame seeds and serve.
Notes / Tips / Wine Advice:
For prawn cocktail,
mix together the grated rind of 1 orange, 4 tablespoons gluten-free mayonnaise and 1 tablespoon gluten-free tomato ketchup in a small bowl. Shred ½ small iceberg lettuce and divide between 4 glass bowls. Top with 400 g cooked peeled prawns, then pour over the mayonnaise. Serve sprinkled with 1 tablespoon toasted flaked almonds and 1 tablespoon chopped coriander.