Nattō

Nattō comes from a bacterium, Bacillus subtilis natto, that turns cooked soybeans into a sticky, ammonia-scented mass. Legend credits a sack of beans forgotten in rice straw during an eleventh-century campaign. Mito, in Ibaraki, has been its industrial capital since the 1880s. You beat it with chopsticks to draw out the threads, season it with mustard and soy sauce, and pour it over hot rice. The dividing line is sharp: loved in the east, largely refused in the west.