Heat oil in a saucepan over high heat. Cook the beef, in batches, until browned. Remove and set aside.
Add onion and garlic, cook for 2 minutes, then add the mushrooms and beef to the pan. Cook for a further 3 minutes until the mushrooms have softened.
Add the carrots, herbs, tomato paste, and 1 ½ cups of stock. Bring to the boil, while stirring, then reduce the heat and simmer for 35 minutes, stirring occasionally.
In a jug or bowl, combine remaining ½ cup stock with cornflour until smooth. Stir into beef mixture. Bring to the boil, stirring constantly. Cook for 5 mins, stirring occasionally until the sauce thickens.