Beef Stroganoff

Name: Beef Stroganoff
Prep time: 20 min
Cook time: 30 min
Ingredients: 600 g Beef Fillet; 25 g Butter; 1 Onion, finely chopped; 250 g Button Mushrooms, thinly sliced; 1 tsp Dijon Mustard; 400 ml Beef Stock; 1 tbsp Lard or Coconut Oil; 2 tbsp Soured Cream; 1 tbsp Brandy (optional); Salt, pepper and chopped parsley (to taste)