This Sunday, the new restaurant inside the iconic Bevo Mill will open its doors to diners for the first time. But that's not the only excitement — brand-new Das Bevo Bierhall (4749 Gravois Avenue) is also announcing that a beloved St. Louis institution will be at the helm of its kitchen.The catering company attached to Sugarfire Smokehouse, Sugarfire Events, is taking the helm at Das Bevo, the restaurant's owners announced in a press release yesterday.…