The East Bay has many contenders to burger immortality: Barney's, Café Rouge, Christopher's, Wood Tavern. But comparisons are tricky, since each operates in burger genres whose differences range from slight to whopping. There's gourmet, fast-food, and the most popular, a kind of hybrid. Elmwood District burger joint Flame has gourmet aspirations, but a recent visit revealed it to be squarely in the hybrid camp: Whatever points Flame racked up for using only grass-fed beef, it lost them to prefab freezer fries. (If you can abide a burger without fries, skip them altogether, especially since you have to pay extra.) Weirdly, in an era obsessed with sources, no one at the restaurant knew where the beef came from. Pressed, a manager said only that it was local. Pressed further, she revealed it was from Piater in Petaluma, producer we've never heard of). Whatever the source, grass-fed beef is lower in fat than grain-fed, which becomes obvious when you try to grill it medium-rare (it cooks unevenly and dries out fast). But Flame succeeded, while also getting a slight char on the outside. In fact, the meat turned out to be too juicy for its lightweight sesame bun, whose bottom quickly sogged out. True, the burgers here might not be as glamorous as the ones down the street at Wood Tavern, but grass-fed beef makes them guilt-free. Well, as guiltless as a carnivore can get in Berkeley.