Preheat grill pan. On a well floured surface, roll or pat the dough into a rustic, oblong shape, about 1/4-inch thick. Brush the crust with a thin layer of olive oil, and dust liberally with za'atar. Lay the oiled side down onto the hot grill. Once the dough looks set, in about 2 minutes, lightly brush with more oil, dust with za'atar and turn the crust over. Sprinkle with salt. Cut into large wedges and serve while warm.