Season the meat with salt and pepper and rub with the garlic. Place in a heavy pot and surround with the carrot celery, and 1 onion. Cook, covered, for about an hour or until there is almost no water. The add water to cover and simmer for an hour and a half.While the meat is cooking, slice the remaining 2 onions and saute slowly in the oil until brown.Remove the meat from the heat and let cool. Drain and coarsely grind with all the onions, adding a little at a broth from the meat if needed to make it moist enough to handle.To make the dough, mix the oil, salt, and water in a bowl. Gradually stir in the flour until a medium-soft dough is formed. Place on a floured board. Knead until the dough is smooth and soft. (A food processor works well for this.)Cut the dough into 3 portions. Roll out each piece of dough into a rectangle about 1/8 inch thick. Cut into 2 inch squares. Fill each square with about a teaspoon of the meat mixture. Dipping your fingers in flour, fold over into a triangle, and crimp closed. Join the 2 ends together like a little ring, as you would a tortellini or a wonton.. Repeat with the rest of the kreplach. If you like, you can freeze the krepler at this point. To do so, place them on a cookie sheet in the freezer and, when frozen, transfer them to plastic freezer bags. Otherwise, refrigerate until ready to use.To cook the krepler, bring about 10 cups of water to a boil in a big pot. Add the salt and about 20 krepler at a time. When the kreplach have risen to the top, cool with a strainer to a bowl filled with chicken soup, serving about 3 kreplers per person.