Heat the olive oil in a large frying pan over a medium-high heat.
Add the sliced beef and cook for 3–4 minutes until browned, then remove from the pan and set aside.
In the same pan, add the onion and cook for 4–5 minutes until softened.
Add the garlic and mushrooms, then cook for a further 5 minutes until the mushrooms are tender.
Stir in the flour and paprika, mixing well to coat the vegetables.
Gradually pour in the beef stock, stirring well so the sauce stays smooth.
Add the Dijon mustard and bring the sauce to a gentle simmer.
Stir in the dairy-free cream, then return the beef to the pan.
Cook for another 3–4 minutes until the beef is heated through and the sauce has thickened slightly.
Season with salt and pepper to taste, then serve with parsley and your choice of rice, mashed potato, or gluten-free pasta.