I stopped making plain grilled cheese: 3 things Germans put in it — and it turns into a proper meal

Then a German friend watched me make one and reacted the way I imagine a French person reacts to instant coffee. Politely. With visible pain. She then rebuilt the sandwich with three things from her fridge, and I have not gone back.

Here is the part where I tell you the three things, because I am not a monster.

The holy trinity, in order of how much they change your life

• Sauerkraut. Yes, the stuff you ignore in the back of the fridge. Drained, warmed, piled on top of the cheese. It cuts through the fat like it has a personal grudge.
• German sausage. Bratwurst if you want spice and heft, bockwurst if you want something herby, a plain frankfurter if you just want smoke. Sliced lengthwise so it lies flat, because structural integrity matters.
• Onions. Caramelized if you have patience, quick-pickled in mustard and vinegar if you don't, or the crispy fried kind (Röstzwiebeln, which is a word I now say out loud in the grocery store for no reason).

That's it. That's the whole trick. The sauerkraut brings acid, the onions bring sweetness, the sausage brings the thing that makes it a meal instead of a snack. Grilled cheese, but it has a job now.

A plain grilled cheese is a sandwich. A grilled cheese with a bratwurst in it is a reason to sit down.

The bratwurst has rules, apparently

This is the part where my friend got stern. You do not just fry a brat and shove it in. You simmer it first, ideally in beer with a knob of butter and some onion, then finish it in the pan or on the grill. It comes out plump instead of shriveled and tastes faintly of a beer garden, which is the point.

If that sounds like too much effort for a Tuesday, a smoked sausage straight from the pan will still make the sandwich better than it was. Effort is a spectrum.

Things you can do once you've stopped being scared of it

Once the base is down, the sandwich becomes a choose-your-own-adventure:

• Throw a few slices of apple or a spoon of cranberries into the sauerkraut while it warms. Sweet-tart against the sausage, very Christmas-market. (The sauerkraut-apple-Gruyère version is basically a Reuben that gave up on the meat, and it's excellent.)
• Swap the sad white bread for a pretzel roll (Laugenbrötchen). Burnished outside, soft inside, salt on top. The sandwich now looks like it has a passport.
• Cheese is flexible. Swiss, Muenster, Gouda, American if you want the melt, Gruyère if you did the caramelized onions and want to pretend you made French onion soup.

Grilled cheese purists will have feelings about this. Eric Greenspan, a chef who built an entire restaurant on grilled cheese, once told a radio host there are "bigger problems in the world than whether or not a tuna melt qualifies." I feel the same way about a bratwurst. The sandwich doesn't need to pass a purity test. It needs to be eaten.

Purists can keep their two ingredients. I'll be over here with a sandwich that has a sausage in it and a pretzel roll for a roof.

Dinner, technically

Here's what happened: I made one for lunch, then made another for dinner, then made two on Saturday for people who came over and one of them asked for the recipe as if it were a recipe. It is not a recipe. It is three things you already own, stacked on cheese.

The grilled cheese was never the problem. It was just under-employed.