Empty the can of beer into a medium saucepan. Add 1/2 beer can of water. Add fresh Brats.
Cut butter into four chunks and add to saucepan. Layer sliced onions on top.
Heat on medium-high on the stovetop. Heat only until the beer ‘dances’. Do not boil the beer.
The Brats will be gray in color but not completely cooked when you remove them.
Place brats on the grill and cover to prevent flare ups. Don’t cook too fast; they need to cook through.
While the brats are grilling, bring the beer sauce to boil for about two minutes. Reduce the heat and keep it warm while the Brats finish cooking on the grill.
When the Brats are finished cooking, remove them from the grill and place them in the beer sauce once again to soften.
Partner with mashed potatoes and a seeded roll for a classic German lunch.