Heat a grill to high (450° to 550°). Combine tapenade, parsley, and mixed herbs in a small bowl.
Lay steak on a work surface between 2 sheets of plastic wrap. Using a meat mallet, pound until an even 1/4 in. thick. Peel off top plastic wrap, spread tapenade mixture all over steak, and roll up so grain of the meat runs lengthwise. Tie at 2-in. intervals with kitchen twine.
Rub outside of steak with oil and season generously with salt and pepper. Grill, turning occasionally, until grill marks appear all over and an instant-read thermometer inserted in center reaches 125° for medium-rare, 15 to 20 minutes.
Transfer steak to a cutting board, tent with foil, and let rest 10 minutes. Remove kitchen twine and cut crosswise into thin (1/4 in.) slices.