If a time-traveling Henry David Thoreau were ever to find himself in present-day Manhattan craving a cheeseburger, the Underground Gourmet would know what to do. We’d send the reducetarian poet to 7th Street Burger, a counter-service hole-in-the-wall that opened in June in the old Caracas Arepa Bar space. The motto of this bare-bones establishment is “Going Back to Simple,” and judging by the length of his menu, owner Kevin Rezvani is wholly committed to the company slogan. The old-fashioned pegboard lists a whopping four food items: a single cheeseburger, a double, an Impossible burger, and fries. That’s it. The lack of choice keeps volume up, waste down, and ordering speedy. The burgers are bigger than sliders, smaller than ShackBurgers, and come one way only: topped with American cheese, pickles, and proprietary sauce on a griddle-toasted Martin’s potato bun. This is, thinks Rezvani, how God intended burgers to be as well as loosely packed, onion-smashed, crisp-edged, and spectacularly greasy. One bite and you see the man’s point. It’s one of the best new burgers in town.