Wisconsin is not necessarily known for its health food. I have a hard enough time explaining cheese curds to people, not to mention why they must be breaded and deep fried. But today's recipe I blame on the Germans -- namely German influence on Northeast Wisconsin cuisine.
Down the road from Lambeau Field is Kroll's, a small-town diner. You seat yourself in any of the booths, browse the menu, and when you are ready to order, you press a button next to the table to summon a waiter. Kroll's has a wide menu, but is particularly known for its burgers. You can order hamburgers, or bratburgers from the menu. And while not on the menu, you can ask for a combo burger, which is a hamburger patty and a bratburger patty. And what makes Kroll's burgers unique is that each burger is served with a pat of butter between the bun and the meat. No, the bun isn't buttered per se, but a pat of butter is put directly on the underside of the top roll, along with the other condiments. The butter is mostly melted by the time you eat the burger.
Now, let's step back a minute: bratwurst. Bratwurst is a staple of Wisconsin grilling. Brats are usually in link form, and are often boiled (usually in lager), grilled, or both (boiled in beer, then seared at the end). Brats are also often made in patty form, and cooked as you would a hamburger (with a few limitations, as I will get to in the recipe itself).
Now, when I moved from Wisconsin to California in 2000, I simply could not find bratwurst in local stores. Nobody carried it. Same deal when I moved from California to Nevada in 2002. However, over the years, grocery stores started carrying brat links, usually Johnsonville brand (a company based in Sheboygan, WI). Today you can find both raw and cooked links in many grocery stores, so I'm assuming the brand has gone national.
Combo cheeseburger, Kroll's style
Calorie count: you don't want to know
* 1 lb lean ground hamburger
* 1.25 lb bratwurst (5 quarter-pound links), raw, not pre-cooked
* 8 hamburger buns
* 16 slices American cheese
* Toppings: Yellow mustard, sauerkraut, onions
Toast a hamburger bun. While the bun is toasting...
Take a bratwurst link and remove the casing. Start at the top and cut down the side of the link, then the casing should be able to be pulled off in a single, sticky piece. Cut the link into two, and take one of the 2 oz halves and form it into a thin patty. Take 2 oz of hamburger and also form it into a thin patty. (See pictures below.)
Grill both patties. This should take no longer than a few short minutes, since the patties should be "fast food" thickness.
When bun is toasted, add a pat of butter and condiments. The bratwurst is the star of this burger, and Northeast Wisconsin tradition dictates that only 3 condiments are acceptable for bratwurst: onions, yellow mustard and sauerkraut. You may subtract from this list, but you may NOT add. ESPECIALLY not ketchup. I personally go with just the mustard.
Layer hamburger, cheese, bratburger, cheese. Serve with fries and/or a pickle.
Makes 8 burgers, plus a leftover bratwurst link to do with as you please. Since you're only left with one, I'd skip the beer bath and go straight to the grill.
(By the way, the malt vinegar is decidedly a [New] England thing, and not a Wisconsin thing. Most of my extended family is from New England, so I'm allowed to cross cultures a bit.)