Place the water in a large pot and add the chicken cubes, onion, garlic and season with salt.
Bring the pot to a boil, then simmer on low heat for 2 ½ hours, until the meat becomes tender and comes easily off the bone.
Meanwhile, make sure to skim away the foam that rises to the surface of the water and add more hot water if necessary to maintain the level of the broth.
Once the meat is cooked, transfer it from the broth to a plate and remove any bones. Take out the onion and garlic from the broth as well and retain the liquid.
Prepare the sauce by soaking the ancho and guajillo chilies in warm water for 25 minutes.
Once softened, drain them and put them in the blender along with the garlic, onion and oregano, along with a little of the water where they soaked. Blend until becomes a smooth sauce.
Add oil to a skillet and and heat it over a medium high heat. Add the blended chilli sauce and season with salt to your taste. Once the sauce begins to bubble, simmer, stirring constantly for about 25 minutes.
Strain the sauce into the broth to avoid any clumps. Add the meat and simmer the mixture for 10 minutes.
Next, add the corn and season to taste with salt and pepper and continue cooking until the corn softens.
Serve the Pozole con Pollo immediately, or allow to rest for a while to let the flavors develop and serve hot at a later time. 
Add the garnish of your choosing on top along with toast and lemon pieces on the side.