Preheat the oven to 200C/180C Fan/Gas 6.
To make the pink pickled onions, pour 100ml/3½fl oz water, vinegar, sugar and salt into a saucepan and bring to a simmer for 1 minute. Pour over the red onions and leave to pickle for 30 minutes.
To make the salmon, cut the salmon into two large pieces and place on a baking tray, skin-side down.
Mix the oil, paprika, onion powder, garlic powder, chilli powder and lemon zest in a small bowl to create a marinade.
Cover the salmon in the marinade. Season with salt and pepper and roast for 10–12 minutes.
To make the slaw, place the hispi cabbage, red cabbage and spring onions in a bowl and season with salt and pepper. Bring the mixture together with the mayonnaise and soured cream and set aside.
To make the guacamole, place all of the ingredients in a bowl, season with salt and pepper and mix to combine.
To serve, carefully place a tortilla over the flame of a hob, using flameproof tongs, until charred and crisped up. Repeat with the other tortillas.
Place the tortillas on a large board. Spread on the guacamole and top with the slaw. Use a fork to scrape the salmon off the skin and lay the salmon on top of the tacos. Garnish with the coriander and a squeeze of juice from the lime wedges and serve.
