PREPARING THE DOUGH
Mix all of the knish dough ingredients (flour, baking powder, kosher salt, lightly beaten egg, melted and cooled unsalted butter, distilled white vinegar, and lukewarm water) in a large bowl.Mix with a large spoon or your hands until dough forms. Once the dough has formed, knead the dough for 30 seconds until smooth dough forms. Do not overwork the dough, or your knishes will be tough.

Cover the dough, and let it rest in the refrigerator for a minimum of 30 minutes (or let it rest in the refrigerator overnight).

PREPARING THE FILLING
In a large pot, add the cut Yukon gold potatoes. Cover the potatoes with 2 inches of cold water. Add in 2 tablespoons of kosher salt, and bring to a boil. Once the water is boiling, reduce to a simmer. Cook for 20 minutes or until the potatoes are soft and ready to mash.Drain the potatoes, and place them in a large bowl. Mash the potatoes with a potato masher. Mix in the cream cheese in small pieces, so it will melt.

Set the bowl of mashed potatoes and cream cheese aside.In a large stainless steel sauté pan, melt 2 ounces of butter. Add in the julienned onions, and generously sprinkle with kosher salt and freshly ground black pepper. Cook on medium-high heat, while stirring occasionally. When the onions start to caramelize, add in a half cup of dry sherry. Scrape the bottom of the pan with a wooden spoon to pull up all of the caramelized bits.

Continue cooking until the onions are a deep golden brown. Finish by deglazing the pan with the remainder (half cup) of the dry sherry. Cook while scraping the bottom of the pan until the dry sherry is reduced. Add the onions into the bowl with the mashed potatoes and cream cheese. Mix in the Fullblood Wagyu pulled beef and minced chives. Season to taste with kosher salt and freshly ground black pepper. This is your Fullblood Wagyu beef fillingPlace the filling in the refrigerator to cool.

PREPARING THE KNISHESPull the filling from the refrigerator, and set it on the counter. Preheat your oven to 375°F.Divide the dough into 2 pieces. On a lightly floured surface, roll the dough out into a rectangle that is 1/16 of an inch thick. Let the flattened dough rest for 2 minutes. Then, cut out as many 3-inch circles as possible. Gently knead the scrap/unused dough back into a ball. Cover it, and set it aside.

Note: The scrap dough can be re-rolled up to 2 times before it becomes to tough to work with. Add one ounce (about the size of a ping pong ball) of the Fullblood Wagyu beef filling in the middle of each 3 inch circle of dough. Gently pull the dough around the filling and up to the top until it has folded over and completely encased the filling.

Place the knishes on a parchment-lined baking sheet. Leave 2 inches of space between each knish. Note: You will need 2-3 baking trays to accommodate all of the knishes.Using your thumb, make an indent in the top-middle of each knish.

FINAL STEPS
Using a pastry brush, carefully brush each of the Fullblood Wagyu beef knishes with the egg wash.Sprinkle each knish with dried onion, poppy seeds, and sesame seeds. Bake at 375°F for 30 minutes or until the knishes are golden brown. Serve the Fullblood Wagyu shredded beef and caramelized onion knishes warm.Enjoy!