Preheat oven to 220c. with a roasting tray inside.
Cut potatoes into 2cm chips, place in a pot of cold salted water and bring to the boil.
Drain well, dry off excess water, and carefully place in the oven tray with 2 tbsp olive oil, and salt. Cook for 10 minutes, then toss chips into the pan and return to oven.
Meanwhile season steak with salt and pepper and heat fry pan on high heat until smoking. Add remaining oil to the pan and quickly sear the steak on both sides, then place in oven for 6 minutes (for a medium-rare to medium steak).
Take steak out of the oven, check chips, and give a good shake if required. Rest steak for 4-5 minutes, giving chips time to finish cooking.
Remove chips from oven and crumble blue cheese over. Serve with steak immediately.