According to the famous steakhouse chain Ruth Chris, the appropriate temperature for cooking a tenderloin steak is 1800 F. Personally, I do not think the Traeger is capable of achieving a temperature hot enough to properly seer a steak, even when using Grill Grates, but some might disagree.
I love the smoke flavor that can be achieved by cooking a steak at low temperature (under 225F) until it reaches an internal temperature of 125F (rare). Then I sear it quickly on a very hot gas griddle or in a carbon steel skillet on a gas stove. That is known as reverse sear.
Some people on the forum use a flame thrower such as the GrillBlazer GrillGun to sear the steak after cooking. The temperature of the flame is close to 3000F, so it will get the job done quickly. You have to keep the flame moving across the steak to prevent burning the meat.
You can also do a normal sear. You sear it first and then finish cooking it to your desired temperature on the Traeger. That might be the best option if your guests prefer different degrees of doneness.
Some people have tried cooking steaks by removing the drip tray and flame shield from their Traeger and cooking the steak directly above the burn pot. That is likely to be as hot as you can get on the Traeger. Put your Grill Grates on the bottom rack, as close as you can get to the radiated heat from the burn pot.
