Best of Boston

Burger slinging has come a long way from the Bartley’s-Sully’s turf wars of yore. Now a groundswell of ground-beef mania has chefs experimenting with custom meat blends, artisanal bunwork, and umami-boosting hocus-pocus. Along divergent paths, Middlesex (smoky bacon, griddled pickle, ciabatta) and KO Prime (foie gras, yuzu aioli, toasted-interior bulkie) raised mundane chuck to dizzying heights. But Radius (aged cheddar, lemon-horseradish mayo, housemade milk bun) tops them all with a mountain of crispy frizzled onions—which, as it turns out, is a little-known shortcut to gastro-enlightenment.