Carefully wash the fish under running water. Using a large needle, pull a thread through the lower jaw and tail end of the fish until they bend round. Bring plenty of salt water to the boil.
Wash the lemon thoroughly and cut into slices. Add vinegar and lemon slices. Cook the trout in it at low heat for about 15 minutes. For the vegetables, peel and wash the carrots and potatoes.
Clean and wash the leek. Cut vegetables into fine strips. Melt 1 tablespoon of fat. Fry the vegetables for about 3 minutes while turning. Deglaze with a little salt water and orange juice. Cover and cook for another 5 minutes.
Melt the remaining fat. Wash and chop the dill. Arrange fish and vegetables on a plate, sprinkled with dill. Garnish with lemon and orange slices and parsley as desired. Add liquid fat exra.