Heat a frying pan and place the steak in on one side, with a touch of olive oil.
Cook for 3 minutes on one side until properly sealed, then turn over and cook for a further 2 minutes until sealed, then do all the edges of the steak that haven’t been cooked for 30 seconds or so.
Once all sealed, add in the mushrooms, shallots & garlic, salt & pepper and place in the oven for 12 minutes on 150 degrees (or until rare – medium rare).
Take out the steak and rest in a warm spot for 10 minutes.
Put the pan on the stove again over a high heat and cook the mushrooms & shallots until nicely browned.
Add in the cavolo Nero and just wilt.
Take out all the ingredients and place on the plate.
Add the red wine into the pan to deglaze and reduce right down, then add in the butter - a bit at a time constantly stirring off the heat until you get a nice sauce consistency.
Slice the steak and pop onto your veggies and drizzle with your sauce.