Chop the cabbage into thin strips and transfer it to a Dutch oven. Pour in the water and sauerkraut juice, then cover with a lid and simmer for 25 minutes, or until the cabbage is tender.
Dice the onion and sauté it in melted butter over medium heat until soft and fragrant. Stir in the aromatics (caraway seeds, bay leaves, marjoram and allspice berries) and mustard, cooking for 1 more minute to release their flavors. Once done, add the mixture to the simmering cabbage.
In a large skillet, melt the butter over medium heat. Stir in the flour to create a roux, cooking for about 1 minute until golden and slightly nutty in aroma.
Transfer the roux into the cabbage mixture, stirring well to combine. Let it simmer for a few more minutes, allowing the flavors to meld and the sauce to slightly thicken.
Garnish with fresh dill and serve warm.
Notes
Toast the spices – lightly toasting the spices enhances their aroma and flavor.Don’t skip the roux – cooking the flour in butter until golden adds a subtle richness and helps the cabbage develop a silky texture.Don’t overcook the cabbage – cook just until tender but still slightly crisp.