Have the butcher grind the meat twice, then mash it in a mortar to make sure it is completely pulverized or use a food processor. Set the meat aside together with any juices.
Heat the oil in a skillet and saute the onions and green pepper or 1-2 hot peppers until the onions are softened. Add the tomatoes and cook until the mixture is thick and well blended, about 5 minutes longer. Cool the mixture slightly.
Put the beef and its juices into a saucepan. Stir in the sauteed onions, green pepper or hot peppers and tomatoes, known as the sofrito, and 8 cups cold water. Mix well.
Bring to a boil over moderate heat, stirring with a wooden spoon. Add the rice or noodles and simmer, still stirring, until tender, about 15 minutes. At this point, season to taste with salt. If salt is added earlier the meat and the liquid, which should be completely blended, may separate.
Some cooks believe that constant stirring is the most important step, others believe the adding of salt is the important factor.
Superstition has it that if anyone who does not enjoy cooking is present in the kitchen they may cause the So'O-Yosopy to separate and spoil the dish.
Serve with a baked sweet potato or a thick slice of broiled yucca (cassava), or both, and Sopa Paraguay, Paraguayan Corn Bread. Recipe for corn bread is posted.
Sprinkle, if liked, with grated cheese. Water biscuits may also be served with soup. Serves 6.