Wash the potatoes thoroughly, cut them into slices and place them on a baking tray lined with baking paper. Sprinkle with oil and season with salt. Bake in a preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for 35-45 minutes.
Roast the pumpkin seeds in a pan without fat until golden brown, remove. Peel ginger and cut into pieces. Wash parsley, dab dry. Pluck the leaves from the stalks, except for something to garnish.
Wash lemon hot, grate dry, peel in zests. Halve the lemon and squeeze 1 half. Ginger, 25 g pumpkin seeds, half lemon rind, parsley and 125 ml oil in the universal chopper to pesto.
Season to taste with salt, pepper and lemon juice. Wash the fish, dab dry, cut into pieces and turn in flour. Heat 2 tablespoons of oil in a coated pan. Fry the fish for 2-4 minutes on each side, depending on the thickness, and season with salt and pepper.
Cut the remaining 1/2 lemon into slices. Arrange potatoes and fish, sprinkle fish with pumpkin seeds and lemon zests and sprinkle with pesto. Garnish with parsley and lemon slices.