Brush the bratwursts with olive oil and place them on the grill. Grill for about 8 minutes, flipping once, until the bratwursts are cooked through.
Meanwhile, melt the butter in a large skillet over medium heat. Add the onions and cook, stirring occasionally, until the onions are golden and caramelized, about 10 minutes.
In a small bowl, whisk together the mustard, honey, Worcestershire sauce, salt, and pepper. Set aside.
To serve, place the bratwursts on a platter and top with the caramelized onions. Serve with the mustard sauce on the side.
Interesting Facts
Wisconsin is the birthplace of the bratwurst.
Bratwurst is one of the most popular sausages in Germany.
Bratwurst is typically served with sauerkraut or potatoes.