Cook the carrots in boiling salted water for approx. 15 mins. until just soft, drain and leave to cool. Roll out the dough, cut off 8 long strips (each approx. 1 cm wide). Wrap each carrot in a strip of dough, place on a baking tray lined with baking paper. Brush the dough with oil, sprinkle with sesame seeds and fleur de sel.
Approx. 25 mins. in the centre of an oven preheated to 220°C. Remove from the oven, allow to cool slightly on a cooling rack.
Mix the sour single cream, vinegar, oil, sesame seeds and wasabi paste, season with salt. Using a sharp knife, make a hole in the thicker end of the carrots, insert the sprigs of chervil, serve with the dip.