Heat a frying pan over a medium/high heat.
Add 1lb (450g) of ground beef, break up into small lumps with a spatula and cook for about 4 minutes, stirring occasionally, until browned.
Meanwhile, finely chop 1 large onion and stir it into the mince.
Thinly slice 2 cloves of garlic and add to the mince and onions. Season with 1 teaspoon salt and ½ teaspoon black pepper. Mix well and sauté over a medium heat for a further 3-4 minutes, until the onion is caramelized.
Slice 10oz (300g) button mushrooms and add to the pan. Cook for 4-5 minutes to soften the mushrooms.
Use the spatula to push the mince closer to the edges, leaving a small empty circle in the middle of the pan. Melt 1 tablespoon of butter.
Add 2 tablespoons of flour and cook for a minute while stirring the butter into the flour to form a smooth paste.
Season with 1 tablespoon Worcestershire sauce, 2 tablespoons Dijon mustard and mix all well together with the mince.
Pour in 1 ½ cups (375ml) beef stock and gently stir to make sure the flour dissolves.
Simmer for 2-3 minutes until the sauce thickens slightly.
Turn off the heat. Add 150ml (⅔ cup) sour cream or crème fraîche and stir to incorporate the cream into the sauce.
Check the seasoning and adjust if necessary.
Serve with finely chopped fresh herbs and enjoy!
