Peel potatoes and cut into 1 cm slices. Peel the cucumber, cut in half lengthwise and remove the seeds. Cut into 1 cm thick slices.
Sauté potato slices in butter, deglaze with white wine and pour in the soup. Cover and simmer about 10 minutes. Add cucumber and simmer another 5 minutes, until the vegetables are al dente. Stir in sour cream and season with salt and pepper.
Season fish fillets with salt and pepper and fry on both sides.
Mix well herbs with 1 tbsp. lemon juice, 2 tbsp. olive oil and a little salt.
Arrange fish on the vegetables and garnish with herbs.