Place the brisket in a pot, add some oil and cover with water. Add the onion, garlic and salt to taste. Cook over high heat with the lid on for an hour and a half or until the meat is very soft.
Once the meat is done, remove it from cooking and cut it into small pieces.
Heat about two tablespoons of oil in a pan and add the meat, fry over medium heat until it turns a golden colour.
Put the meat in a bowl and use the same pan to reheat the tortillas.
Serve the tacos with a double tortilla and garnished with finely chopped onion and coriander, lime and the salsa of your choice.