In a large bowl, mix the all-purpose flour, sugar, yeast, and milk to form a dough.

Divide the dough into 4 portions of 110g each, and add different vegetable and fruit powders to each portion to create dough of different colors.

Roll each color of dough into long strips, and pad them up, divide them into 12 portions. Cover the portions to prevent them from drying out.

Divide the remaining white dough into 12 portions, roll them into smooth balls, and cover them.

Flatten the white dough balls, place the colored dough inside, and wrap the white dough around it. Seal the edges and place them on steaming paper.

Put the steamed buns in a steamer, cover them, and let them ferment for 1 hour or until they have risen to 1.5 times their original size.

Steam the buns on high heat for 10 minutes after the steam has risen.

Turn off the heat, wait for 5 minutes before opening the lid, and then enjoy your rainbow steamed buns. If you cannot finish them, you can store them in the freezer and reheat them later.