Bring the chile, pork, and 3 quarts of water to a boil in a Dutch oven or large pot. Simmer for 1 hour.
Stir in the onions, garlic, posole, and salt and continue to simmer over low heat until the posole has absorbed the flavors. This will take roughly 30 minutes.
Serve hot in bowls with some of the liquid, or drain with a slotted spoon and serve as a side.