I apologize for hijacking this thread with this but I think these tips might be useful to the brat fans. I just wanted to throw one last thing out there.
You realize you can freeze caramelized onions, right?
So if you happen to make a metric ton of them and portion them into freezer bags or little containers and freeze them then you can thaw them along with your brats (if you are like me and try to buy them on sale or in bulk as opposed to buying and making immediately) and then warm those onions in a pan with your beer and make your brat bath.
If I am going to a friend's house to bbq, I will make the beer and onion brat bath and put it in a disposable aluminum pan and take my show on the road. Then pop the whole thing on their grill (to rewarm and stand at the ready) and then sear them off when we are ready to eat.
This little trick also works nicely for a bbq where you are trying to prep ahead so you aren't trying to make everything at once. Make those onions ahead and store them in a disposable aluminum pan, then when you are getting ready to cook, you can pop that pan on the grill, add beer and brats and get ready to sear.
And for my little smokey joe, I use a disposable loaf pan for my beer onion bath. It will hold several brats but because it is narrow rather than wide, it takes up less real estate on your grate.
Tips - I got'a million of 'em...