Flake in the salmon, then season well with salt and pepper and add the lemon zest and dill ... sauce, put the egg yolk in a bowl or food processor with a generous pinch of salt and the mustard.
Meanwhile, mix together a second marinade in a small bowl with the yoghurt, wholegrain mustard, chillies, sugar and dill. Mix the fish with the second marinade and set aside until you are ready to ...