Heat 1 tablespoon Olive oil in a frying pan and add 500 g Braising steak (chuck roast). Cook the chunks of meat for about 2 minutes until all sides are browned.
Meanwhile chop 1 Onion, 1 Leek, 10 Mushrooms and mince 2 Garlic cloves.
When the beef has browned, remove it from the frying pan and put in the slow cooker bowl. Add the vegetables to the frying pan and cook for 5 minutes.
Place the cooked vegetables in the slow cooker bowl with the beef and add 500 ml Vegetable stock, 250 ml Red wine, 2 tablespoon Wholegrain mustard, 4 tablespoon Fresh rosemary, 2 tablespoon Tomato puree and 1 pinch Sea salt and black pepper.
Cook on low for 7 hours or high for 4 hours.
You don't have to sear the meat first, however it really does make a difference to the finished dish as it seals all the flavour in.
Root vegetables work really well in this stew, however you can give it a green boost by adding some leafy greens about 30 minutes before the stew is ready.
You don't have to serve this stew with anything. You could add some potatoes to the stew and cook it all together.