Melt half of the vegan butter in a pan. Stir in the flour well until there are no more lumps.
Add the vegetable stock while stirring. Then bring to the boil briefly.
Turn down the heat. Add the vegetable cream, white wine and the remaining butter. Add the mustard and lemon juice to the pan. Season to taste with salt and pepper.
Let the sauce simmer for about 5-10 minutes so that it thickens. Season again and serve!