Peel, wash and slice the potatoes. Heat tablespoons of oil in a large frying pan. Fry the potatoes for about 12 minutes, turning occasionally. Season with salt and pepper
Heat 1-2 tablespoons of oil in a second pan. Fry the fish fingers on both sides over medium heat for 5-8 minutes until golden brown
In the meantime heat the fat. Sauté the flour in it until golden brown. Deglaze with broth. Let simmer for about 5 minutes. Stir in cream and mustard. Season to taste with salt, pepper and cucumber water
Cut the cucumbers into slices. Wash the dill, shake dry and cut finely. Arrange the fried potatoes, fish fingers, cucumber, dill and mustard sauce and garnish