1/4 c. olive oil
1 shallot, minced (about 3 T.)
6 garlic cloves, minced
2 T. minced fresh rosemary
1/4 tsp. salt
1/4 tsp. pepper
1 (1.5 lb.) flank steak, trimmed
Vegetable oil for cooking grate
Process the oil, shallot, garlic, rosemary, salt, and pepper together in a blender or food processor until smooth. Prick the steak with a fork about 20 times on each side, then rub both sides of the steak evenly with the paste. Wrap with plastic wrap and refrigerate for at least 1 hour or up to 24 hours.
Turn all the burners of your grill to high, cover and heat the grill until hot, about 15 minutes. Use a grill brush to scrape the grate clean. Lightly dip a wad of paper towels in oil. Holding the wad with tongs, wipe the cooking grate. Place the steak on the grill and cook covered (if using a gas grill) until the steak is well browned on both sides and thickest part registers 120-125 degrees on an instant-read thermometer (for medium-rare), 8-12 minutes, flipping the steak halfway through.
Transfer the steak to a carving board, tent loosely with foil, and let rest for 10 minutes. Slice the steak thin, against the grain and on the bias, and serve.