The Sumo Orange Is a Cross Between the Mandarin and a California Navel Orange Sumo is a name that fits this new orange because of its size (it is one of the largest mandarins) and its distinctive topknot, like a sumo wrestler's. But wrestling is not an issue with the Sumo orange because its bumpy skin is so easy to peel. A cross between the mandarin and a California navel orange, it took 30 years to develop in Japan, where it is called Dekopon and highly prized; at a half-pound to a pound, a single fruit sells there for as much as $8. Last year Sumos were first grown in California and sold mainly on the West Coast, but now they are available in the New York area. The easily segmented oranges are sweet, with good texture and no seeds. Sumo Citrus are sold at Whole Foods for $2.99 a pound; Gourmet Garage, $3.99 a pound; Eataly, $5 a pound; and baldorfood.com, $20 for seven, plus shipping. They will be available through March.