Chop your potatoes and veg into bite size chunks and toss with 1 tbsp oil and the seasonings listed above.
Add to the air fryer and roast for 30 minutes at 180 degrees, tossing and shaking them halfway through. In a pan, heat 1 tbsp of oil until hot and fry the seasoned steak on both sides for 3 minutes per side (more if you want it well done).
Take the steak off to rest and add the sliced mushrooms & garlic into the same pan.
Deglaze the pan with some beef stock and build your sauce with a generous crack of black pepper (or crushed peppercorns), dash of cream and the cornstarch dissolved in a little water.
Allow the sauce to thicken and taste to adjust the seasonings.
Serve the roasted root veg on a plate with the sliced rested steak over the top and pour the reduced mushroom & peppercorn sauce over the top.