Heat the oil in a large frying pan over high heat. Cook the steaks, in 2 batches, for 3 minutes each side or until browned. Transfer to the slow cooker.

Add the butter to the pan. Cook until foaming. Add the onions. Reduce heat to medium-low and cook, stirring often, for 10 minutes or until browned and tender. Add the garlic and cook, stirring, for 1 minute or until aromatic.

Add the tomato paste to the frying pan and cook, stirring, for 1 minute. Add the stock, Worcestershire sauce, thyme and bay leaves. Bring to a simmer. Pour over the steaks in the slow cooker. Cover and cook on High for 5 hours or until beef is tender. Add thick sliced carrots if you like.

Combine the cornflour with water. Add to the slow cooker. Cook for 20 minutes or until the liquid has thickened slightly. Season. Stir through the parsley. Add a cup of frozen if you like too.

Sprinkle with extra parsley. Serve with mash, if using.