Heat oil and butter in a large frying pan on a medium to low heat
Thinly slice mushrooms and onion and place in frying pan and sauté for 10 minutes
Once sautéed remove from frying pan and set aside
Chop the beef into cubes and place into frying pan and brown up for 5 minutes
Add the brandy and continue cooking until the alcohol has burnt off
Add the beef stock, whole grain mustard, bay leaf, salt and pepper
Scrape the bottom of the frying pan with a spatula to release any brown bits that might be stuck to the bottom and will add to the flavour of the sauce
Add the onion and mushrooms back into the frying pan and for 3 minutes so it’s bubbling away and everything is heated through
Stir in the crème fraîche and parsley to combine all the ingredients and remove from heat and serve immediately
Enjoy!