Wash the pork knuckle and beef tail and cut it into pieces. Excess fat can be cut off if desired. In a saucepan, add the chopped beef tail and knuckle, pour cold water and put on an intense heat. When boiling, remove the resulting foam. Cover the pan with a lid, reduce the heat to low and cook the meat for 5-6 hours. 2 hours before cooking, add the onion (whole onion), Bay leaf (2 PCs.), black pepper (1 teaspoon), salt and ground black pepper to taste.