I made another batch of mustard yesterday using this recipe from Serious Eats as a jumping off point. If you've been following this thread, you'll know I made the SE recipe a while back and liked it. Nonetheless, the world is filled with mustard recipe options and I want to continue experimenting. What I made yesterday was a modification of the SE recipe, the point of which was to see how small changes would affect the result.
The intent of the modification(s) was to tone down the intensity of the mustard slightly as a couple of people thought it was "too hot." I could see their point even though I was fine with it. The changes were simple. Instead of 3/4 cup of brown mustard seed I used 1/2 cup brown and 1/4 cup yellow. I also substituted brown rice vinegar for the white wine vinegar in the original recipe.
The yellow mustard seed was a good choice, but I'm not so sure about the brown rice vinegar. It seemed to mute the brightness of the mustard somewhat. As this will be an ongoing experiment, I'll revert back to the original vinegar with the next batch. I also want to experiment with different mustard seeds and different styles of mustard. Dijon will be next.