My first brat was a Johnsonville at the June Sprints at Road America, Elkhart Lake WI in 1967.
Back then they were grilled and then sliced in half length ways, and then cut in half at the middle.
They would put 3 of the slices on a hamburger bun. These days they serve the brat whole on a hot dog bun.
Every once in a while I use the hamburger bun method. Johnsonville Italians are pretty good as well.