Potato Knish

Ingredients

• For the dough:
• 2 1/2 cups all-purpose flour
• 1 teaspoon baking powder
• 1/2 teaspoon kosher salt
• 1 egg, beaten
• 1/2 cup vegetable oil
• 1 teaspoon lemon juice from 1 lemon
• 1/2 cup water
• For the filling:
• 1 pound russet potatoes, peeled and cut into 1 inch pieces
• Kosher salt and freshly ground black pepper
• 2 tablespoons butter
• 1/2 cup finely sliced scallion whites and greens

Directions

1. Make the dough by whisking the flour, baking powder, and salt in a large bowl. In another bowl, whisk the egg, vegetable oil, lemon juice, and water together. Add the liquid mixture to the flour mixture and stir with a wooden spoon until it becomes a dough. Knead it with your hands until it feels smooth and holds together, about 1 minute. Cover the dough snugly in plastic wrap and leave it at room temperature for 1 hour, or refrigerate it up to overnight. If it has been chilled, bring it back to room temperature before you continue.
2. For the filling, put the potatoes in a large pot, cover them with water, salt the water generously, and bring it to a simmer. Cook until a knife slides into the potatoes easily, about 10 minutes. Drain them, then let them sit for a few minutes to dry before adding the butter and mashing until nearly smooth. Stir in the scallions, then add salt and pepper to taste. Cool the filling to room temperature.
3. Set an oven rack in the middle position and heat the oven to 375 degrees F. Line a baking sheet with foil or parchment paper.
4. Cut the dough in half and roll one piece into a broad, thin rectangle that is less than 1/4-inch thick. Shape half of the filling into 4 balls and arrange them along the lower edge of the dough. Roll the dough loosely up and around the mounds of filling, then twist and pinch the dough between the mounds to separate them. Leave one end of each knish open, and pinch the other end closed. Set each knish on the baking sheet with the sealed side underneath, then press lightly on top to make a low, compact roll. Do the same with the remaining dough and filling, then brush the knishes with beaten egg.
5. Bake the knishes until they turn golden, about 45 minutes. Serve right away.