Poke the bratwurst with a fork to just break the casings a bit.
In a deep skillet, place half of the onion slices, bratwurst, caraway seeds, and the beer. Bring the beer to a boil and turn the heat down to a rolling simmer. Simmer the brats for 15 minutes.
Turn the heat off the braised brats and allow them to sit in the braising liquid while you move on to step 2.
Preheat your George Foreman Grill to high. Brush 1 tablespoon of the olive oil on the grill plates.
Grill the remaining onion slices until just charred with grill marks on both sides. Set the onions aside to serve as a topping.
Remove the bratwurst from the liquid to paper towels to dry off. Discard the braising liquid.
Coat the grill plates, or the bratwurst, with the remaining tablespoon of olive oil.
Place the brats on the grill, close the top, and grill for approximately 6 minutes rotating every 2 minutes for even browning. Remove the brats to a plate.
Open the rolls or slice open the bread pieces. Place these on the grill and toast lightly in the bratwurst drippings. You may have to do this in 2 batches.
Serve the bratwurst inside the rolls with your desired toppings.