Corn-fed beef burgers in Central Square

Burger Nation is rapidly polarizing into two Americas, the 99cent poor and the foie-gras-topped rich, leaving the middle-class gut dangerously healthy. Saving the day, Four Burgers.Four's a Spartan, metal-and-mirror spot from the Paramount/21st Amendment guy, who took an extensive tour of Cali and NYC's premier meat-wich mavens (In-N-Out, the Shake Shack, etc) to determine the optimal path to affordable Beantown fatness. The menu's stupid-simple, with four variously-pattied burgers cooked to spec for $7-8: all-natural corn-fed Brandt beef (lettuce, tomato, pickle, choice of cheese), Salmon (sesame slaw, soy mayo), Blue Mango Veggie (guac, salsa, lettuce, tomato), and a Turkey number slathered with cranberry chutney for the taste of freshly-pulverized Thanksgiving. To offset the protein, there's homemade waffle chips, hand-cut fries, sweet potato fries, or a mesclun green salad with your choice of balsamic, lemon vinaigrette, or a supplemental pinch of pride.If your binge needs a night-cap, FB serves up homemade brownies, a giant Toscanini ice-cream sandwich, and floats made with Harpoon Brewery Rootbeer, plus now wine and the real stuff -- because if you want to unite rich, poor, and middle, you'd better have beer.