For the best results, fry bacon until it is fully crisp.
This soup is inspired by the mustard soups of the Netherlands, where there were once scores of small grocers who made their own mustard. Most of those producers have faded into history, but one, Abraham’s Groningen Mustard Factory, remains. It is located in a small village in Eenrum, a short drive from Groningen, and includes a museum and a restaurant. They may be best known for their mustard soup, which has inspired many versions, including several with bacon.