1. In a pot, boil the chicken breast with 1/4 of an onion, salt, and garlic until the chicken is soft. Remove the chicken from the broth, reserving the broth. Shred the chicken and set aside.
2. In a blender, add 2 cups of the reserved chicken broth, tomatoes, chipotle sauce, 1/4 of an onion, garlic and oregano. Blend and set aside.
3. Slice the remaining 3 onions. In a saucepan, add the vegetable oil and saute the onions for 5 to 7 minutes. Then add the shredded chicken and the sauce from the blender. Add salt to taste. Let it cook for 15 to 20 minutes at medium/low heat.
4. To serve, spoon onto a tostada, add some shredded lettuce and a dollop of sour cream, and enjoy! You could also serve it over rice, in a taco, in a burrito, the options are endless!Serves 4-6
