This versatile and addictive condiment goes well with a variety of grilled meats, but pairs especially well with chef Anthony Meidenbauer's bratwurst. This recipe has been scaled down for use at home.
Heat the oil in a large pot over medium heat. Add the yellow onion and jalapeño, and lightly sweat them. Deglaze the pan with the vinegar and beer, and allow it to reduce by half over medium heat. Add all the mustard seeds and mustard powder and simmer for 5 minutes. Add the yellow mustard, dijon mustard, sugar, honey, and 1 cup of water, and allow the mixture to simmer for 20 minutes, until the flavors have melded.
Transfer the mixture to a blender. (Be careful since hot liquids expand when blended.) Blend the mixture to a smooth consistency. Season with salt and pepper, to taste. Mix the cornstarch and remaining water together to form a slurry. Blend in the slurry until the desired consistency is achieved. Transfer to a container, and once cooled, refrigerate.