Peel, wash and chop the carrots. Clean, wash and cut leek into thin rings. Steam prepared vegetables and lentils in hot lard for about 5 minutes. Season with pepper and dried coriander.
Deglaze with tomato juice and stock. Cover and cook for about 40 minutes. In the meantime wash, quarter and seed the tomato. Cut the flesh into small cubes. 2 minutes before the end of the cooking time, fold into the lentil vegetables.
Season to taste with salt and vinegar. Wash the fish fillet, dab dry and cut into pieces. Sprinkle with lemon juice, salt a little and turn lightly in flour. Fry in hot oil while turning for about 4 minutes.
Serve garnished with lemon slices and fresh coriander.