Remove the chicken from the pot and shred it. Take the half onion that is left along with the onion used to cook the chicken and finely chop it. In a medium sauce pan, heat up oil on medium high heat. Add the onions, cook till soften and slightly golden brown. Add the minced garlic saute for 20 seconds. Add the cumin, chili powder, and oregano. Saute the spices for 20 seconds and then add the shredded chicken. Give everything a good mix and season to taste. Let the mixture cook for 2-3 minutes. Turn off the heat and keep chicken mixture aside.