Roughly chop the sunflower seeds, roast them in a pan, mix with 80 g butter, season with salt and pepper and refrigerate.
Peel the kohlrabi and potatoes, wash them, cut into large pieces and cook in salted water for about 15 to 20 minutes. Wash the kohlrabi green, pat dry, roughly chop and set aside.
Heat milk. Pour off the kohlrabi potato mixture (I still leave some water in the pot, after all there are still a few vitamins in it), add milk and butter, coarsely mash and season with the spices.
Wash the plaice fillets, pat dry, drizzle with lemon juice, season with salt and turn in flour. Heat the oil in a pan, add the plaice fillets and fry until golden brown on both sides.
Arrange the plaice fillets with the sunflower seed butter and kohlrabi mashed potatoes, sprinkle with kohlrabi green and serve.