1. In a large pot, put the brats, onions, caraway seeds, and beer. Bring to a boil, then turn down and simmer for 15 to 20 minutes. Remove brats and set aside.
2. Pour liquid through a colander and take the onion mixture left in colander and put in large skillet with a drizzle of olive oil. Turn heat on under skillet to low, cover skillet, and let simmer very slowly until caramelized, stirring occasionally. This will take at least 20 to 25 minutes if done correctly. The onions will become golden brown, soft, and sweet.
3. When ready to eat, set grill to medium heat. Put brats on grill and cook about 10 minutes, turning often so all sides get good grill marks.
4. Serve on buns with mustard and a generous helping of the caramelized onion on top. (Please! No ketchup.)