Make the filling:

• In a large skillet over medium-high heat, saute the ground beef and grated onion until just cooked through, breaking up the meat with your spoon.  Drain off any excess fat. Sprinkle in the allspice, salt, and pepper. Stir well to combine.
• Allow the meat and onion to cool.
• Stir in the egg, salt, and pepper to taste. Set aside.

Make the dough.

• In the bowl of a food processor, add the eggs, salt, and water.  Pulse to combine.
• Slowly add the flour, a few tablespoons at a time, pulsing after each addition.
• Add in enough flour to make a medium-soft dough that forms a ball.
• Remove from the food processor.  Divide into 2 balls and cover with a moist towel.  Set aside and allow to rest for at least 10 minutes.
• Lightly dust a large cutting board with flour.
• Working quickly, roll out 1 ball of dough until about ¼-inch thick.
• Use a pizza cutter to cut the dough into strips that are 2-inches wide.  Then cut each strip into 2-inch squares.
• Place 1 teaspoon of the meat mixture in the center of each square.
• Use a finger to moisten all of the edges of the dough and then fold the dough into a triangle and press the edges together very firmly.
• Repeat with the remaining ball of dough.

To cook:

• Bring a large pot of chicken stock to a full rolling boil  Drop the kreplach into the stock and cook, uncovered, for 15 minutes.  If you are making chicken soup, you can drop them right into your soup during the last 15 – 20 minutes of cooking.
• Alternately, you can saute the kreplach in a skillet with chicken schmaltz or oil until golden brown on both sides.