The most famous form is
岐山臊子面 from Qishan county, Shaanxi. Tradition calls for nine characteristics: thin, firm, light noodles; hot, sour, spicy broth; and fragrant, slick, greasy topping. Diners sip only the soup and topping, leaving the broth for the next bowl - a relic of the 'sacrificial noodle' (
哨子面) village banquet tradition.
