Cook the rice in 400 ml salt water for 20 minutes. Wash fish, dab dry and cut into 8 pieces. Peel and chop the shallots. Boil shallots, bay leaf, juniper berry, peppercorns and lemon juice in about 1 litre of salted water.
Let the fish simmer at low heat for about 10 minutes and take it out. Pour the cooking liquid through a sieve, measure 1/4 litre and boil down to approx. 100 ml in a pot. Wash herbs, dab dry and chop coarsely, except for some dill for garnishing.
Add to the brew and puree with the cutting stick of the hand mixer. Stir in the yoghurt, but do not let it boil up any more. Season sauce with salt and pepper. Arrange two fish pieces each with some sauce, rice and lemon slice on a plate.