Prep potato: Microwave potato until cooked. Peel, mash, and spread around a bowl to cool.
Activate yeast: Combine lukewarm water and yeast. Let sit briefly to bloom (optional).
Mix dough: Combine flour, mashed potato, salt, and yeast mixture. Mix until mostly combined.
Add oil: Knead in olive oil until incorporated.
Develop gluten: Knead for several minutes until smooth, OR fold the dough every 15 minutes for an hour, tucking the edges under for the final fold.
First Rise: Let dough rise, covered, until doubled in size (about 1 hour).
Shape: Divide dough into 6 pieces. Shape into tight balls (see notes).
Final rise: Arrange on a baking sheet, cover, and let rise until doubled (about 1 hour).
Bake: Preheat oven to 180°C (350°F). Brush buns with soy milk, sprinkle with seeds. Spritz oven with water and bake for 14 minutes, or until golden.
Finish: Brush with olive oil or vegan butter and cool on a wire rack.