Heat the vegetable oil in a large heavy-based saucepan over medium heat.
Cook the bacon (if using!), stirring, until browned, then transfer to a small bowl until needed.
Brown the chuck steak in batches, seasoning with salt and pepper, then remove from the pan.
Melt the butter, then fry the carrot, celery and onion for 10 minutes, or until softened.
Add the flour and cook, stirring, for 3 minutes.
Add the Vegemite and tomato paste and cook for a further minute.
Add the red wine and cook for 2 minutes, then gradually add the beef stock to produce a thick stew.
Reduce the heat to low, return the beef to the pan with the bay leaves, thyme and sliced mushrooms.
Cover and simmer for 2 hours, or until the beef is tender.
If the stew is too watery, remove the solids and reduce the liquid by boiling uncovered until thickened to the consistency you like.
Stir the bacon and red wine vinegar through the stew and serve with mashed potato and peas.
