Make the masa: Put the flour into a large bowl. In a small pot, bring the oil, water and salt to a boil, over high heat, about 3 minutes. Transfer the mixture from the heat and cool until lukewarm. Add this mixture to the flour and toss together until all the flour is absorbed. Knead the mixture until a dough is formed. Cover with plastic wrap and refrigerate for at least 4 hours or overnight.

Make the filling: Place the meat, onion and water into a pan over medium high heat and use a wooden spoon to break up the meat. Cook the mixture until most of the water is absorbed, about 10 minutes, stirring occasionally. Add the salt and pepper and stir. Transfer the mixture into a heatproof bowl and cool until the mixture is at room temperature. Stir in the matzo meal or breadcrumbs and raw egg, then fold in the hardboiled eggs. Mix until combined well. 

Preheat the oven to 375 ̊.

Shape and fill the borekas: Crack the 2 eggs into a small bowl and whisk well. Set aside. Transfer the dough onto a clean work surface. Break off a piece of dough about the size of a heaping tablespoon or walnut. Use your hands or a rolling pin to flatten the dough into a circular piece of dough that is 3-4 inches in diameter. Brush a bit of the egg wash onto the edges of the dough. Place a tablespoon of filling onto the center of the dough. Fold over one side of the dough onto the other, creating a semicirclular shape and covering the filling. Press the edges to seal the filling. Twist the edges into a crimped pattern if desired. Brush the top of the boreka with egg wash and gently transfer it onto a parchment lined sheet tray. Repeat the shaping and stuffing the remaining dough and filling into borekas. Place the borekas about 1 inch apart on the tray.

Bake at 375 ̊for 40 minutes or until the borekas are well browned. Transfer out of the oven and eat the borekas warm or at room temperature.