Preheat the oven to 180 degrees (convection 160 degrees). Peel the potatoes and cut into slices or cubes, cut the pumpkin into bite-sized wedges. Mix everything with 2 tablespoons of olive oil and 1/2 teaspoon of salt and spread on a baking sheet. Bake in the oven for 35 minutes.
Chop the parsley, cut the spring onions into slices and mix with the horseradish, pumpkin seed oil, 3 tablespoons of olive oil, honey, lemon juice, salt and pepper.
Take the vegetables out of the oven and mix with the dressing. Add the beetroot, divide the trout fillets and pour over them.