1. Heat the olive oil in a non-stick frying pan then add the sliced onion and cook on a medium heat for around 5 minutes until soft.
2. Add the crushed garlic and cook for a further 2-3 minutes then add the butter.
3. Once the butter is foaming a little add the mushrooms and cook for around 5 minutes or until completely softened.
4. Season well then remove from the pan to a side plate.
5. Add the plain flour into a bowl with a pinch of salt and pepper then toss the sliced steak into the seasoned flour mixing well to make sure all is fully coated.
6. Add the steak pieces to the pan, adding a splash of oil if the pan looks dry, and fry for 3-4 minutes, until well coloured.
7. Add the onions and mushrooms back into the pan with the steak and whisk in the crème fraiche, English mustard and beef stock.
8. Bring to a simmer and cook over a medium heat for around 5 minutes.
9. Season with black pepper and serve with some chopped fresh parsley.
Pasta or rice are a great accompaniment to this dish!
Using chicken breast instead of the steak also makes a tasty dish!
For a vegetarian option simply just swap the beef stock for vegetable and add extra mushrooms instead of steak!