Preheat your oven to 425°F.
Trim any silver skin from the bottom of the tri-tip and sprinkle the entire thing with seasoning salt, gently rubbing it into the surface.
On the stove, heat olive oil over medium-high heat in a large oven-safe skillet. Once oil is hot place tri-tip, fat-side down, in the pan. Turn heat down to medium-high and cook for 4 minutes, or until well-seared. Flip meat and place pan in the oven.
Roast for 10 to 15 minutes per pound (start checking the internal temp at about 20 minutes for a medium-sized roast). Cook until internal temperature in the thickest part of the meat reads 135°F for medium-rare to 145° for medium (the roast in the photos was pulled at 145°F). Tent with foil to keep warm and allow meat to rest for 10 minutes before slicing.
Slice roast against the grain by cutting it in half at the center point and then across the grain on each end and enjoy!