To pickle the red onion, thinly slice into rounds, sprinkle with salt and sugar and pour over 2tbs of the lime juice. Set aside for 10 minutes.
Stir the lime zest through the crème fraiche and place in a serving bowl.
Use a stick blender to mash the avocadoes into a smooth puree, add coriander and 1 tbs lime of juice then season to taste. Place in a serving dish.
Preheat a heavy based fry pan and quickly heat tortillas, then keep warm, wrapped in a clean tea towel.
To serve, place the Huon Salmon, tortillas, pickled onion, avocado and crème fraiche in the centre of the table so everyone can make their own tacos as they like.