Slice the cabbage into thin strips. I used a mandoline slicer for this.
Chop the onion finely. Peel, core and chop the apples.
Melt the butter in a large heavy-bottomed pot. Sauté and onions and apple until the onion becomes translucent.
Add the cabbage and lemon juice. Stir.
Sprinkle with 1 - 2 tsp salt, then add the vinegar, wine, broth, bay leaves, cloves, juniper berries and sugar.
Cover and simmer on a low heat for 1 1/2 - 2 hours, stirring every 10 -15 minutes.
Mix the flour with a little water in a cup to make a runny paste. Add this mixture to the cabbage and stir in to thicken the sauce.
Add the redcurrant jam, if using.
Taste and season with more salt if needed.
The cabbage can be made a few days in advance and kept refrigerated until needed.