Peel onions, carrots and sweet potatoes. Wash the carrots and sweet potatoes, cut everything into large pieces. Heat butter in a pot. Fry the onions in it until transparent. Steam carrots and sweet potatoes briefly. 3⁄4 Add l water and bring to the boil. Stir in stock. Season with salt and pepper. Cover and simmer for 15-18 minutes.
In the meantime, reduce the currant jelly and vinegar in a saucepan until syrupy. Fry bacon in a hot pan without fat until crispy. Drizzle with maple syrup and glaze briefly in the hot pan. Drain on kitchen paper.
Puree the vegetables in the broth. Stir in the crème fraiche to about 2 tablespoons. Season soup with salt and pepper.
Wash the chives, shake dry and cut into fine rolls, then mix with coarse pepper. Serve the soup with the bacon broken into pieces, balsamic syrup, the remaining crème fraîche and the chives.