Shred smoked salmon. Roughly chop coriander. Put smoked salmon, coriander in a food processor together with the lime zests, juice of other lime, ginger and creme fraiche. Remove the skin from the fresh salmon and break the flesh into large chunks, removing any bones. Add to the processor with salt and pepper, then pulse the mixture until it forms a rough, textured paste. Turn out into a bowl or individual ramekins and chill until ready to serve - up to 3 days.