The term DE-LUMP, AS FLOUR is a cooking instruction that means to SIFT flour. Sifting flour is a process of breaking up any lumps that may have formed in the flour and aerating it. This is done by passing the flour through a sieve or sifter, which is a device with a mesh bottom that separates out the larger pieces of flour. Sifting flour helps to make sure that the flour is light and fluffy, which is important for baking.