Preheat a cast iron grill pan or skillet over high heat.
Rub the roast with the oil, then season roast with salt, pepper, and cumin.
Place the roast into the pan and sear for 8-10 minutes turning until all sides are browned.
Remove the roast from the pan to a plate. Wrap in foil. Allow the roast to rest for 15 minutes.
Preheat the oven to 250 degrees.
Stick a probe thermometer into the center of the roast.
Place the roast back into the cast iron pan. Close the door and attach the probe to the base. Set an alarm to go off at 135 degrees. This should take between 20 to 30 minutes.
Remove from the oven. Wrap the roast in foil and allow at least 15 minutes for it to rest before carving.
Notes
How to cut a center cut roast from a whole tenderloin
The first thing that you need to do is remove the silver skin. It's white and gray membrane that looks shiny. It's not edible. You need to get your knife into the skin and just use the knife and your hands to peel it off until it looks clean.
It's not very hard to do, you just need a good knife that can cut through it.
Once you have it removed, slice the roast into 3 pieces. The center piece should be around 1 ¼ pounds. That is your center cut roast.