COOK IT.
Preheat the main grill to 375°F and the Infrared Side Burner to high.
Season the beef tenderloin with salt and pepper to taste.
Sear the meat on all sides over the preheated Infrared Side Burner.
Transfer the tenderloin to the main grill, insert a barbecue thermometer like Napoleon's Bluetooth Thermometer . Roast the beef using direct heat to your desired doneness. About 15-20 minutes for medium-rare (130°F to 135°F), 20-25 minutes for medium (140°F to 145°F), and 25 minutes for medium-well (150°F to 155°F).
Remove meat from the grill when it is 5 to10 degrees short of desired temperature. Allow the meat to rest at least 10 to 15 minutes as it will come up to your desired finished temperature during that time. This will ensure ideal tenderness.
Sauce
While the Tenderloin is resting, melt 2 tbsp. of the butter with the olive oil in a skillet set over medium-high heat.
Add the shallot and sauté over until the shallot is soft and translucent.
Pour the wine and demi-glace into the skillet and bring the sauce to a boil, continue boiling the sauce until it has reduced by half.
Serve with the finished and sliced Chateaubriand.
