Peel and wash the potatoes. Cut potatoes into 1-1.5 cm pieces. Heat 2 tablespoons of oil in a large frying pan. Fry the potatoes over medium heat for 15-20 minutes, turning occasionally.
Wash the pumpkin, cut in half and remove the seeds. Cut pumpkin first into slices, then into 1-1.5 cm pieces. Heat 2 tablespoons of oil in another large pan and fry the pumpkin for 10-15 minutes.
Clean, wash and drain the rocket well. Coarsely chop the walnuts and add them to the potatoes about 3 minutes before the end of the cooking time. Season with salt and pepper. Put goat cheese on a greased baking tray and sprinkle with brown sugar.
Caramelise the sugar quickly under the grill or with a Bunsen burner. Mix pumpkin, rocket and potatoes in a pan. Place goat's cheese on top, grate horseradish on top and serve immediately.