Preheat the oven to 200C, fan-forced. Line an oven tray with baking paper. Quarter the unpeeled potatoes. Finely chop the parsley, discarding the stems.
Step 2 — Cook potato and peas
Put the potato in a small saucepan of cold salted water and bring to the boil. Reduce the heat to medium and cook for 12 mins. Add the peas, return to the boil and cook for a further 2 mins or until the peas and potato are tender. Drain and return to the pan.
Step 3 — Marinate salmon
While the potato is cooking, combine the cumin and coriander spice blend, 2 tsp olive oil and 1 tsp honey in a shallow dish and season with salt and pepper. Add the salmon and turn to coat.
Step 4 — Bake salmon
Put the salmon on the lined tray. Bake for 6-8 mins until just cooked or cooked to your liking (cooking time may vary depending on thickness of the fillets).
Step 5 — Add spinach
Return the potato and peas in the saucepan to low heat. Add half the parsley and 20g butter, season with salt and pepper and cook, stirring, for 2 mins or until the butter is melted. Add the spinach, cover and remove the pan from the heat. Set aside until the spinach is slightly wilted.
Step 6 — Make dressing and serve
Meanwhile, put the horseradish dressing and 2 tsp white wine vinegar in a bowl and stir to combine. Divide the potato mixture and salmon among plates. Drizzle over the horseradish dressing and scatter with the remaining parsley to serve.