Place the salmon in a large, shallow pan with a lid. Pour in the wine, vinegar and enough water to just cover the fish, then add the bay leaf. Place over a medium/low heat with the lid on and simmer for 10-12 minutes, or until the salmon is just cooked. Remove from the poaching liquid and set aside on a plate. Once slightly cooled, flake.
Place the cauliflower pieces in a steamer over boiling water and steam for 12 minutes or until tender. Blitz in a food processor until smooth, then set aside to cool for a few minutes. Tip it on to a clean tea towel and squeeze out any excess moisture.
Meanwhile, place the potatoes in a large pan and cover with cold water. Bring to the boil then simmer for 12-15 minutes or until soft. Mash until fairly smooth and leave to cool slightly.
In a bowl, combine the cauliflower and mashed potato. Stir in the egg yolk, flaked salmon, cornflour, lemon zest and parsley and season to taste, making sure not to overwork the mixture. Divide the mixture into 8 and shape into patties. Place these in the fridge for 30 minutes to firm up.
Preheat the oven to 160°C/fan 140°C /gas mark 3. In a small bowl, combine the yogurt with the dill and juice of half the lemon and season to taste.
Heat the vegetable oil in a large non-stick pan. Place 4 of the fishcakes in the pan and cook for 2-3 minutes on each side until golden brown. Place on a baking sheet in the oven to keep warm then repeat with the other fishcakes. Cook the peas to packet instructions, then crush lightly with the back of a fork. Serve the fishcakes and peas with the yogurt dip and lemon wedges.