A perpetual line snakes out the door at Little Big Burger, the Pearl District’s first independent fast-food joint, a mere napkin’s pitch from Powell’s City of Books. Suits and dudes, off-duty baristas, Twitter-happy restaurant hunters, even a few hummus-loving yogis, mats in hand, have come looking for instant bliss on a bun. The burgers here sizzle so fast and furious on the open grill that the hiss threatens to drown out the crowd as Michael Jackson shrieks in the background. The ...