Preheat the oven to 200 C (180 C Fan).
Poke the potatoes with a fork then microwave steam them for about 8 minutes until soft. Set aside to cool.
While the potatoes are cooking, fry the onion and ginger in a non-stick pan using the oil (or non-stick Spray) until soft.
Precook the salmon by placing it in the oven for about 10 minutes, until flaky but still pink.
Flake the precooked salmon by breaking it apart with your fingers and removing any bones and skin. Set aside.
Remove the skins from the potato, then mash roughly with a fork. Add the onions and ginger, the lemon zest and juice, and the soy. Combine well.
Gently fold in the salmon into the mix. Be careful not to over-mix to avoid turning into mush. Taste the mix, and season with salt and pepper if necessary.
Roll ball with your hands or use an ice-cream scoop, placing the fishcakes on a prepared baking tray.
Bake for 20 minutes in total, turning fishcakes over after 10 minutes.
Enjoy with lemon wedges, a large fresh salad, and some oven-baked chips.