Potato knishes (corned beef optional)

DIRECTIONS

• To make the dough
• Put flour, baking powder and salt in the bowl or a stand mixer fitted with the dough hook. Mix briefly with a spoon, then use the spoon to make a well in the center of the flour. Pour egg, oil and water into the well, then use the mixer to knead the dough until it is soft and pliable, about 4 minutes. Stop the mixer a few times to bring the flour from the sides of the bowl into the center, then continue to knead.
• Wrap dough with plastic wrap and put in the fridge for an hour and up to a day.
• Turn oven to 375 degrees. Line two baking sheets with parchment paper.
• To make the corned beef filling
• Cover potato with salted water in a sauce pan. Bring to boil over high heat, then cover pan, reduce heat to low, and cook on low simmer until tender, about 15 minutes. Drain in a colander and let potato stand in colander until all steam is out. Transfer to a medium bowl and use a potato masher to mash. Set aside.
• In the meantime, put oil in a non stick pan over medium-high heat, add onion and sauté until golden, reducing the heat to medium if onion browns too quickly. After about 10 minutes, when onion is golden, add chopped corned beef, mix and continue to cook for another 5-10 minutes, until onion is golden-brown. Remove from heat and add to the mashed potato.
• Squeeze all liquid out of the sauerkraut and add to the mashed potato, together with salt, pepper and caraway seed. Mix, and adjust salt to taste.
• For the potato -onion filling
• Cover potato with salted water in a sauce pan. Bring to boil over high heat, then cover pan, reduce heat to low, and cook on low simmer until tender, about 15 minutes. Drain in a colander and let potato stand in colander until all steam is out. Transfer to a medium bowl and use a potato masher to mash. Set aside. In the meantime, put oil in a non stick pan over medium-high heat, add onion and sauté until golden-brown, about 15-20 minutes. Add to the mashed potato, together with salt and pepper. Mix and adjust salt to taste.
• Now prepare the knishes
• Dust a working surface and a rolling pin with flour. Divide dough into two. Roll half the dough to a thin 20” by 12” rectangle, with the long side towards you. Put half the filling at the bottom of the dough, leaving about 2 inches of dough at the end. Stretch the last 2 inches to cover the filling, then roll towards the end that’s further from you to create a long roll.
• Use your hands to seal the two edges. Now use a knife to just mark (do not cut!) the roll dividing it into 8 equal sections. Use the side of your hand to “cut each section”, trying to seal the dough at each section. Then use a knife to cut between the sections.
• Take each section, put in on its’ side (with the sealed dough down) and use your hand to shape it into a round roll, pushing towards the center to create the center dent. Transfer to the lined baking sheet and repeat with the rest of the knishes. Then repeat with the second half of the dough.
• Mix egg yolk, olive oil and water for the wash and use a pastry brush to brush knishes all over. Sprinkle poppy seeds, if desired (if you’re making two kinds of fillings, sprinkle poppy seeds only on one kind, so you can tell which one is which.) Bake for 45 minutes, or until knishes are golden. Rotate and flip between the baking sheets while baking. Serve warm or at room temperature, with or without mustard.