Pour the water and beer into a 2-quart saucepan. Add the onions and whole garlic clove. Bring the mixture to a simmer, then add the bratwurst. Once the liquid returns to a simmer, continue to cook the brats uncovered for 25 minutes."
Remove the saucepan from heat and cover it. Let the brats sit in the liquid until you're ready to grill them. For the most tender brats, I prefer to let them soak for at least 30 minutes, or up to an hour or two.
Light your grill and sear the brats until they’re slightly crispy on the outside. Serve them in a fresh or toasted bun, topped with some of the onions you cooked them with, and whatever additional condiments you prefer. I’m partial to a good old-fashioned dollop of mustard on mine.
Notes
*The beer acts as an flavor booster but can be replaced with equal amounts of water if desired.