First make the dipping sauce. Put the water, sugar and fish sauce in a pot and heat until the sugar dissolves. Then reduce heat and simmer for 2 minutes and leave to cool and then add the limejuice, ginger and garlic. Leave to infuse for at least one hour and strain the sauce.
To make the rolls, grate the carrots and place in a large bowl. Then slice the mango, cucumber, chili, ginger, shitake mushrooms and scallions and add to the bowl and mix everything gently.
Make the marinade by whisking the soya sauce, Mirin and palm together and pour it over the vegetables. Stir the vegetables in the marinade to make sure that it is well incorporated.
To assemble the rolls, soak some rice paper in cold water until it softens, then place on a damp cloth on the counter.Divide the coriander and mint between the rolls and place the marinated vegetables on top. Roll the paper gently but firmly until you have a long cylindrical shaped roll. Slice off the top and tail of it and divide in 4 pieces.