Step 1

Peel and chop the potato to 1" dice. You should have 1 heaping cup of diced potatoes. In a small saucepan, combine the milk and diced potato. Bring the milk to a simmer and cook until the potato is very tender. Stir frequently and watch the pot for boil overs.

Step 2

Remove the pan from the heat. Transfer the milk to a large mixing bowl or the bowl of a stand mixer. Add the butter and use a fork or potato masher to mash the potato into the milk. Add the sugar, salt and egg. Check the temperature. If needed, cool until the mixture is about 110F, or slightly warmer than body temp. Sprinkle the yeast over the mixture.

Step 3

Add 1 cup of the bread flour and mix on low speed to form a thick batter. Switch to the dough hook or use a wooden spoon or spatula to mix by hand. Add the remaining bread flour and mix until the dough clings to the hook and clears the sides of the bowl. Knead for 5 minutes to develop the dough.

Step 4

Turn the dough out onto a floured surface and knead into a smooth ball. Set in a lightly oiled bowl, turning once to coat the surface of the dough. Cover with plastic wrap and set aside to rise until doubled in volume (1 - 1 1/2 hours).

Step 5

Turn the dough out onto a lightly floured surface and knead to form a smooth ball. Divide the dough into 10 equal portions (see note). Roll each portion to a ball and set them a parchment lined baking sheet. Wet your hand and use it to flatten each ball to a disc about 1" thick.

Step 6

Cover the sheet pan and allow the rolls to rise until almost doubled in size (about 1 hour). Press a roll with your finger. If it springs right back it's not ready, if the dent slowly fills in the rolls are ready to bake.

Step 7

Meanwhile, preheat the oven to 400°F.

Step 8

Brush the tops of the buns with egg. Sprinkle each bun generously with sesame seeds. Bake until the buns are golden brown and feel light when lifted off the sheet pan, about 10-15 minutes. Allow to cool completely before slicing.