Peel your white potatoes and dice them and load the potatoes into the slow cooker with half the butter or margarine, salt, pepper, and mixed herbs. Allow to slow cook for 90 minutes on high to create soft mashed potatoes. After 90 minutes put the potatoes to one side in a suitable bowl and add the milk and other half of the butter.
Whilst the potatoes are cooking in the slow cooker, peel and slice your onions and also peel and slice your garlic cloves.
When the slow cooker is done, and you have emptied out the potatoes use the slow cooker on the stovetop to sauté the onion with extra virgin olive oil. Sauté until the onions are similar to hot dog onions and have some colour to them.
Then stir in the garlic and add to the slow cooker the braising steak. Season the braising steak with salt, pepper and half the bouquet garni. Slowly turning it and re-seasoning until it is browned and seasoned on all sides.
Add in the red wine and beef stock and then slow cook for 4 hours on high or 7 hours on low. Then whilst the slow cooker is working its magic mash your potatoes and put to one side.
Remove the braising steak from the slow cooker and allow to rest on a clean chopping board.
Then add a heaped tablespoon of mashed potatoes and the rest of the bouquet garni. Stir and allow it to thicken.
Then slice the braising steak and serve the braising steak with mashed potatoes and onion gravy.