Begin by washing the russet potato thoroughly. Place it in a pot of water, bring it to a boil, and cook until tender, about 20 minutes. Once cooked, drain the water and let it cool slightly. Peel off the skin and mash the potato until smooth. Set aside to cool completely.
In a small bowl, combine the water and 1 tablespoon of sugar from the recipe. Sprinkle the active yeast over the top and let it sit for about 5-10 minutes until it becomes frothy.
In a large mixing bowl, combine the remaining sugar, salt, mashed potato, milk, and egg. Stir until well combined. Add the frothy yeast mixture and mix well. Gradually add the flour, one cup at a time, until a dough begins to form.
Transfer the dough onto a lightly floured surface. Knead for about 8-10 minutes until the dough is smooth and elastic. If the dough is too sticky, sprinkle in a little more flour as needed.
Shape the dough into a ball and place it in a greased bowl, covering it with a clean kitchen towel. Let it rise in a warm area for about 1-2 hours, or until it has doubled in size.
Once the dough has risen, punch it down to release air. Divide the dough into equal portions, roughly 8-10 pieces. Shape each piece into a smooth ball and place them on a greased baking sheet.
Cover the shaped buns with a towel and let them rise again for about 30-45 minutes, until they puff up.
While the buns are rising, preheat your oven to 350°F (175°C). Once the buns have puffed up, bake them in the preheated oven for 20-25 minutes or until golden brown on top.
Remove the buns from the oven and let them cool on a wire rack. Serve warm or at room temperature.
