Finely dice potatoes and fennel, cook in salted water for 4-5 minutes until al dente, rinse and cool.
Cut herring, apple and green cucumber also into cubes – remove seeds from green cucumber – roughly pluck parsley. Mix all ingredients with vegetable oil and white wine vinegar – season with salt, pepper and lemon.
Garnish: Serve with fried or boiled egg, brown bread or lettuce leaves.
Drink: Wheat beer or Riesling wine.