Sift the flour, mix the sifted flour and salt in a large bowl.
Mix in the solid margarine or butter with your fingers, (best to cross cut with two knives). The flour should have an even, coarse texture, with the margarine lumps no larger than a pea.
Beat together the water, eggs, and vinegar in a bowl. Slowly mix into the flour mixture, until you have the desired consistency (it should not be too sticky, but still malleable).
Place the mixture on a floured surface. Knead with the heel of your hand to bring the dough together.
Cover the dough and allow to sit in a cool place for at least an hour.
Roll out the dough until it is about 1/8 of an inch (0.3 cm) thick. Cut into circles about 4-6 inches (10 - 15 cm) in diameter and lightly flour them.
Heat some oil in a large saucepan. Mince the onions and garlic, and add to the pan. Cook until the onions become translucent.
Add the ground meat. Break it up with with a spoon and cook, stirring until lightly browned. Drain off fat.
Mix in the cumin, pepper flakes, and sugar. Adjust to taste.
Chop the hard boiled eggs and halve the stuffed olives. Carefully mix into the meat mixture. Add salt and pepper to taste.
Preheat the oven to 375ºF/200ºC.
Stuff the empanada dough wrappers. Place 2-3 tablespoons of the filling in the center of each wrapper. Dampen the outer perimeter of the dough.
Fold over, forming a semicircle. Pinch a corner of the dough, and then fold that section onto itself. Pinch and pull out another 1/2-inch (1.2 cm) section and fold over, so that it slightly overlaps the first piece. Repeat along the length of the folded side, until you create a braided or twisted seal.
If desired, brush the tops of the empanadas with beaten egg yolk for a nice golden color.
Place the folded empanadas on a greased cookie sheet. Bake 15-20 minutes, or until golden brown.