In a 3-quart slow cooker, combine chicken, chicken stock, cooking sauce, onion, chiles, and garlic.
Cut corn tortillas into thin strips and add to slow cooker, stirring to combine.
Add 1/2 cup water to the pasilla sauce jar, close lid, and shake to incorporate any leftover sauce; add to the slow cooker.
Cook 6 to 7 hours on Low, or until the chicken is nearly cooked. Pull out and shred using fork and knife on a cutting board. Return chicken to pot along with rinsed corn and beans.
Cook an additional 1 to 2 hours, or until the chicken is thoroughly cooked and broth is slightly thickened.
In pot with tight-fitting lid, heat olive oil over medium high heat.
Add rice and brown, about 8 minutes, stirring often to prevent burning.
Add 2 cups water, bring to boil, then cover and turn off stove, leaving pot on hot burner.
Let sit undisturbed for about 20 minutes or until liquid is absorbed and rice is cooked.
To serve, place rice in bowl, ladle stew over all, and garnish as desired
