Heat oil in a large pan over HIGH heat. Brown beef and onion (You may need to do this in batches) then add to slow cooker.
Add carrots, celery, red wine and recipe base to the slow cooker and stir through. Cover and cook for 4 hours on HIGH or 8 hours on LOW (Keep covered during cooking. Cooking times may vary between slow cooker models, we used a 5.5 L appliance).
Serve with mashed potato.
NO slow cooker, NO problem, place prepared casserole in an oven proof dish, cover and cook at 160°C (140°C fan-forced) for 3 hrs or until tender.