wonderrunner, brats are serious buiziness for me,, one of my all time favs. i am happy to see your last attempts with a good roll and just mustard, ketchup has no place on a brat.
i usually grill up a whole onion for two brats, sometimes a bell pepper. next time i make them i'll be sure to post a pic for ya, but i like to lightly grill a brat with sliced onion in the dutch oven, just till the onion is done, the brat will still be pink inside, but, then you take the brat and onions and wrap them in a homemade sourdough (pig in a blanket style) and bake the whole thing in the dutch oven, when the bread is done the brat is perfect.