I'm not a huge mustard fan, so imagine my surprise when I tried mustard soup in the Netherlands and it was amazing. The mill where they ground the mustard was right next door. It was like a cheese soup almost. Creamy, tart, spicy. So good. All of the Dutch mustard was, including with the bitterballen.
For something called "mustard soup" it's INCREDIBLY filling. The taste is fantastic, but neither my wife nor myself could finish our bowls, we're going to have the rest for lunch today.
Part of that may have been that I also whipped up some English muffins for dipping.
I'll say this, Europeans know how to make a soup base that can accommodate any number of ingredients. Some of the best soup I've ever had was just from a big vat of pea soup at a university dining hall in Brussels.