Preheat the oven to 180°C.
In a pan, heat ½ the oil over a moderate heat and sauté the onions and garlic and shallots until soft.
Drain and rinse the sauerkraut and then add to the pan with the wine, stock, bay leaf, lemon zest and pink peppercorns. Cover with a lid and place in the oven for one hour. Check to ensure that it hasn’t dried out. If needed add a little water or a splash more wine.
Meanwhile in a frying pan, heat the olive oil over a moderate heat and sauté the haddock and salmon for 3 minutes on each side, drain on kitchen paper. Repeat with the prawns and mussels for 5 minutes.
At the end of cooking add the fish to the sauerkraut mixture and stir through the cream, return to the oven, and bake for a further 5 minutes. Arrange the sauerkraut evenly onto four plates with the fish on top.