Heat the olive oil in a large saucepan over medium-high heat. Add the beef mince and brown for 4-5 minutes, breaking it up with a spoon.
Add the diced onion, carrots and celery. Cook for 5 minutes until the vegetables begin to soften.
Stir in the tomato puree and dried thyme. Cook for 1 minute.
Pour in the beef stock and add the pearl barley and bay leaf. Bring to the boil.
Reduce heat, cover and simmer for 30 minutes until the barley is tender and the soup is thick.
Remove the bay leaf. Season with salt and pepper and serve hot.