This little-known Japanese fruit now has a cult following

When Jerry Callahan had his first bite of a Sumo Citrus fruit about nine years ago, he knew he'd tried something special. "This is going to go crazy," he thought.

As the group vice president of produce and floral at the grocery store chain Albertsons, Callahan is essentially a produce trend-spotter by trade — and he's eaten a lot of fruit. But he described Sumo Citrus as unique. "The eating experience, there's just nothing like it," he said. The fruit may appear unappealing at first: It looks like a small, wrinkly orange with a knob akin to the top knot worn by the Sumo wrestlers for which it's named. But it's actually a hybrid of navel oranges, pomelos and mandarins and tastes like an extra-sweet mandarin. It peels easily, thanks in part to that knobby handle, and doesn't make your fingers too sticky.