Set slow cooker on sear mode.
Dust steak lightly with seasoned flour.
Heat oil in slow cooker and brown steak in batches.
Remove and put into a bowl or on a plate and set aside.
Add butter to slow cooker and mix with the pan juices.
Add onions and garlic and cook until onions are transparent.
Add red wine let it cook off for about 30 seconds.
Stir in extra flour and cook for 2 minutes.
Gradually add stock, stir until sauce boils and thickens a little.
Add Vegemite, tomato paste and Worcestershire sauce and stir to combine.
Put meat back into slow cooker and stir.
Cook on LOW for 5hrs or until meat is tender.
If it needs thickening just mix 1 tbsp cornflour with a little water mix through and let cook for about 15 minutes.
Taste add salt & pepper if needed.