In a medium skillet, take ground beef with 2 tbsp of vegetable oil over medium heat. When the beef is cooked, add chopped onion into the skillet and cook them together for 5 minutes. Turn the heat of and add chopped parsley, black pepper and salt. Set a side.
In a medium mixing bowl, mix eggs, milk and vegetable oil for sauce.
Take kataifi from the freezer and break it into small pieces in a mixing bowl immediately. Let it thaw for ten minutes. Then add sauce in it and mix it evenly. In a rectangular pyrex, take the half of kataifi and press and spread filling over the first half of kataifi,then spread the second half of kataifi over the filling and gently press.
Preheat the oven to 350 F. Bake for about 45 minutes or until nicely brown.
When it completely cools down, cut the borek into square shapes.