Let's do something different with pasta. Beer, cheese, and German Wurst turn out in a tangy, delicious way!
Cook the pasta according to the directions on the package, then drain it and keep warm. Set aside 1/2 cup of cooking water.
Heat oil in a big skillet over medium-high. Add the sausage and onions and cook, stirring occasionally, until the sausage is browned and the onions are slightly caramelized. Deglaze the skillet with beer, and cook until the liquid is reduced to about 1/4 cup. Take it off the heat, and keep warm.
Heat butter in a medium saucepan over medium heat. Whisk in the flour, and cook while whisking constantly for 1 to 2 minutes. Whisk in milk, and bring to a simmer. Turn the heat down to medium-low, and continue cooking, whisking often, for 5 minutes.
Stir the cheese and mustard into the milk mixture and take it off the heat. Add apple cider vinegar, salt, and pepper, and stir to combine.
Stir the sausage mixture and sour cream into the cheese mixture. Pour that stuff over the pasta, and toss to coat. If the mixture seems too thick, stir in the cooking water you saved. Toss with fresh herbs, and serve immediately.