In a medium (3-quart) saucepan, whisk together the chile powder, salt and 3 cups water. Add the meat and bring to a boil over high heat. Partially cover and reduce the temperature to keep the liquid at a gentle simmer until the meat is fall-apart tender, about 1 hour. Let cool for a few minutes, then use a slotted spoon to remove the meat. Pour 1/2 cup water into a small bowl and whisk in the masa or masa harina until thoroughly blended. Return the sauce to a boil over medium-high heat. Strain in the masa mixture, and whisk until the mixture boils and thickens slightly. Remove from the heat, taste and season with additional salt if necessary.
Use fingers or 2 forks to break the meat into coarse shreds. Scoop into a bowl and stir in the raisins and olives along with one cup of the thickened sauce. You can save the rest of the sauce, rewarm it and serve it over the tamales, if you wish.