To provide a new food material unimaginable from conventional Gan-modoki (bean curd mixed with sliced vegetables and fried in deep fat) by improving dough as a base for producing an expanded soybean protein food, i.e. soybean protein itself, composed mainly of soybean protein such as Gan-modoki and Abura-age (fried bean curd).

Conventional dough for Gan-modoki prepared by using powdery soybean protein as a main material is drastically modified to give a cooked bakery product having a soft crust, smoothly meltable in the mouth, directly eatable in contrast with the Gan-modoki necessary to be boiled in a broth and having good palatability similar to bread, by adding a relatively small amount of starch such as wheat flour to dough, adding egg and adjusting the water content of the dough to a proper level.