There is a unique sweet snack in Lanzhou, a city in northwest China. It is a kind of congee made of the local pottasche, pea, red dates and sugar. It can be eaten by people of all ages in winter and summer.

Literally, ash means pottasche, which is a type of dietary alkali unique to Lanzhou and extracted from a plant. The bean is the pea. The congee is a pea soup with dietary alkali. Alkali helps to soften the peas and make the soup inexpressibly fragrant. The soup is not sweet or bitter, but tastes like something between sweet and bitter. The soft peas enter the mouth with the aroma of red dates. The peas are not completely turned into paste, or that will be less interesting. It is slight hard when chewed, with sweetish aroma coming out.

According to the ancient method, a big-mouthed earthen pot is kept on a coal stove, and there is blackish purple well-cooked congee in the pot all the time. After filling a bowl with the thick congee with ash beans, you can enjoy it by standing or squatting. The soup is warm rather than very hot, just acceptable to the mouth. It cannot be hotter or cooler. In the past, the ladies who had just watched a play or played cards would order a late snack, which must be ash bean on a little food stand at a street corner with a kerosene lamp on.