Although I do pick at this straight from the refrigerator if I'm lucky enough to have any left over, I really advise you to make this last minute, as you're about to plate up.
Peel the carrots, cut into long slices, and then julienne them (i.e. cut into matchstick-like strips). Trim and halve the scallions and then julienne as well. Seed the chillies and also cut into juliennes, and finely chop the cilantro. Combine all the julienned vegetables and the chopped cilantro in a bowl. In another bowl mix the lime juice, fish sauce and superfine sugar, and dress the vegetables with this.