The Bratwurst Mystery

How do you make this Wisconsin classic?

I have been thinking about bratwurst for days.  What started as an idea for a simple cookout on my little Webber Grill has now completely consumed me because I simply can't find the right recipe.  The question eventually led me to walk into Hot Dougs on a recent Wednesday and ask Mr. Doug himself what was in the sausage.

But first, do you know?  What is it, exactly, that makes a bratwu...