Hello everyone. . .first time long time. . .
I've been going through a Polish cookbook of mine with the desire to make Polish Rye like many places here in Chicago. Just wondering if anyone has a suggested source for "powdered sour" which the author describes as "An integral ingredient that gives Rye bread its distinctive mellow, tangy, sour flavor. Powdered sour is available at any quality baking supply house or through mail order"