Below is a simple recipe for Bratwurst that, a far as I am concerned, is the only way it should be prepared. Using this method makes the end product very juicy and adds a little hint of smoky flavor.:
2 Medium white onions
1 can Sapporo beer
Extra virgin olive oil
Set up your grill for indirect cooking. It cannot be overemphasized that cooking bratwurst over direct heat is a bad idea. The high fat content of the sausage, when heated too quickly, will cause the skin to split open. This means delicious juicy goodness ending up in your drip pan and not in the food. Bad. Anyone who has grilled bratwurst on too high a heat knows exactly what I mean. It tastes good, but a sausage all split open and oozing flavor is not good eats.
Once your rig is up to about 225, in go the brats. You can coat with oil, but I generally do not and I recommend not trying to season them as they have their own great flavor and my experience has been that the seasonings do not dissolve and have a gritty consistency when eaten. I throw on a handful of dry wood chips directly on the hot coals (Brazilian style) for some smoke. Put the lid on and walk away. Don't peek for at least 20 to 30 minutes or you will let the heat out. Patience is a virtue that will pay off here.
I usually put a small pan directly over the coals adjacent to the meat to get the onions going right away. You can either chop the onion and sauté or cut them in half, coat in oil and a little salt and pepper and put them directly on the grill. I have also seen people wrap them in foil to caramelize. The goal is to cook the onions until they are brown. This process of cooking the sugary onion until it caramelizes brings out it's natural sweetness and is a great compliment to the sausage.
When Are They Done?
After about 30 to 45 minutes, the sausage should be done. You can tell because they are not "mushy" and, if the skin has stayed intact, they look like they are about to burst. That is the juicy goodness I mentioned before. If you must, you can verify doneness by sacrificing one with a knife.
The Final Touch
Now that you have yummy, juicy, sausage goodness barbecued to perfection and caramelized onions, you could just grab a bun and some mustard and proceed to the eating. But why stop there when you can add one more layer of flavor?
In a saucepan, add the bratwurst and onions, following with the beer. Bring to a simmer. This is called a "jacuzzi" and it brings beer flavor to the party as well as being a great way to keep the brats warm until service.
I have eaten bratwurst and onion just by themselves and that is good. My favorite way to eat them is on a soft roll with mustard, jalapeno, and sauerkraut. A 2nd Sapporo, or your beer of choice, is also a good accompaniment.
Remember, if you don't need one hand to dab the sweat from your forehead, you need more peppers!