Combine olive oil, salt, pepper, garlic powder, onion powder, cumin, and chili powder in a small bowl to make a paste. Rub 1/2 of the paste on each side of the flank steak and wrap tightly with plastic wrap. Refrigerate for at least 2 hours or overnight.

Preheat a gas grill for high heat and lightly oil the grate.

Sear the steak for 3 minutes, turning counter-clockwise once after 1 1/2 minutes to create grill marks. Flip steak over and sear an additional 3 minutes. Reduce flame to medium-high and continue to cook 5 minutes more for medium-well, or until desired temperature.

Remove steak from grill and let rest 10 minutes before slicing.