PQR is not just another slice joint. Angelo Iezzi is a Roman pizza master, taking a science-based approach that includes a 96-hour dough-fermentation process. The crust is crisp-bottomed and airy on top, cut into squares and simply sublime. Tempting toppings abound: spicy soppressata, tuna and artichoke or potato and truffle among them. Order at the counter, and the staff will rapidly heat your slice and serve it on a tray.