1- Dissolve the yeast in the lukewarm water you will use in the dough and let it sit for 10 minutes. Add 2 tablespoons of flour in it, mix and leave for another 30 minutes.
2- For the filling, peel the potatoes, cut them into small pieces, boil them and mash them into a puree. Add the egg and butter into the mash and mix.
3- In a separate bowl, mix the remaining flour, milk, salt, sugar and ginger powder. Mix the filling and yeast mixture. Work until you get a homogeneous dough with shiny and non-sticky surface.
4- Place the dough in one big or two small pans floured and greased.
5- Cover the dough with a damp cloth and raise it for about 1 hour in a warm environment until it reaches the height of the mold.
6- Bake it in a oven preheated at 230-240 °C for about 40 minutes.
7- Remove the potato bun from the mold and cool it. Sprinkle icing sugar on it before you serve.
