Tenderloin Steak Chateaubriand with Chateau potatoes

PREPARATION

1. Melt the butter and olive oil together in the large skillet over medium high heat
2. Season the beef with salt & pepper to taste
3. Place the meat on the pan and do not move it for 3 minutes
4. Turn the tenderloin onto its other side and brown for 3 more minutes
5. Place the tenderloin onto a tray to rest covered for 5 minutes
6. On the same pan place the chopped shallot and saute until softened
7. Pour the wine into the skillet and bring the sauce to a boil, scraping the browned bits on the bottom of the pan
8. Continue boiling until the sauce reduces by half
9. Add the demi-glace to the sauce and boil the mixture for a minute until thickened
10. Slice the tenderloin and serve immediately with the sauce and potatoes.