Pork tenderloin with mustard sauce

Name: Pork tenderloin with mustard sauce
Prep time: 20 min
Cook time: 35 min
Total time: 35 min
Yield: 4 portions
Ingredients: 450 g pork tenderloin; 100 g button mushrooms; 75 g dry vermouth; 100 g milk; 60 g onions; 2 tsp wholegrain mustard; 1 tsp hot mustard; 1 chicken stock cube (for 0.5 l); 1 tsp salt; 1 pinch ground black pepper; 2 tbsp crème fraîche; 1 heaped tbsp cornflour (starch); 2 - 3 sprigs fresh parsley