2 medium russet potatoes (128 grams), peeled and cut into 1-inch pieces
1 tablespoon (9 grams) active dry yeast
½ cup (100 grams) granulated sugar, divided
7 to 7½ cups (875 to 938 grams) all-purpose flour, divided
¼ cup (57 grams) unsalted butter, softened
2 tablespoons (18 grams) kosher salt
1 tablespoon (15 grams) fresh lemon juice
2 large eggs (100 grams)
Melted unsalted butter
Flaked sea salt
Directions
In a large saucepan, bring potatoes and water to a boil over medium-high heat; cook until tender, 10 to 12 minutes. Drain, reserving 2 cups liquid. Press potatoes through a potato ricer, and let cool completely.
In the bowl of a stand mixer fitted with the paddle attachment, combine 2 cups reserved potato water (at 110°F), yeast, and 2 teaspoons (8 grams) sugar. Let stand until mixture is foamy, about 5 minutes. Stir in mashed potatoes, 3 cups (375 grams) flour, softened butter, kosher salt, lemon juice, eggs, and remaining sugar; beat at medium speed until smooth. Gradually add remaining 4 to 4½ cups (500 to 563 grams) flour, beating until a soft dough forms.
Turn out dough onto a heavily floured surface, and knead until smooth and elastic, 2 to 3 minutes, sprinkling surface with additional flour as needed.
Spray a large bowl with cooking spray. Place dough in bowl, turning to grease top. Cover and let rise in a warm, draft-free place (75°F), until doubled in size, about 2 hours.
Line a baking sheet with parchment paper, and spray with cooking spray.
Divide dough into 24 equal pieces. Roll each piece into a ball. Place on prepared pan. Cover and let stand in a warm, draft-free place (75°F), until puffed, about 45 minutes.
Preheat oven to 350°F. Bake until golden brown, 25 to 30 minutes. Brush with melted butter, and sprinkle with flaked salt.