To cook in a pressure cooker: In the bottom of a 6- to 8-quart electric pressure cooker, stir together the salsa verde, canned chiles if using, cumin, garlic powder, and onion powder. Add the chicken in an even layer, flipping the pieces once or twice to coat with the salsa mixture. (Tip: Skip the salt for now, as the salt content varies from one jarred salsa to another, and you may or may not need it later.) Close the lid and turn the pressure knob to sealed.
Cook on high pressure for 8 minutes. If cooking chicken breasts, use the quick release. For chicken thighs, allow to naturally release for 10 minutes, and then release the remaining pressure manually. Open the lid and remove the chicken to a plate or bowl. Allow to cool for a few minutes, and then shred with two forks.
If you’d like to reduce the sauce (it’s fairly thin), turn on the simmer function and let the sauce simmer for about 5 minutes, stirring occasionally, to thicken. (I tend to skip this step.) Stir the shredded chicken back into the sauce into the pot. Or you could add the desired amount of sauce to the chicken in a bowl. Taste and season with salt, if needed, and a squeeze of lime juice, if desired. Serve in bowls or in tortillas with toppings of choice.
To cook in a slow cooker: In the bottom of a 6-quart slow cooker, stir together the salsa verde, canned chiles if using, cumin, garlic powder, and onion powder. Add the chicken in an even layer, flipping the pieces once or twice to coat with the salsa mixture. (Tip: Skip salt for now, as the salt content varies from one jarred salsa to another, and you may or may not need it later.)
Cook on low until the chicken is tender and can easily be shredded with two forks, 3 to 5 hours. (Helpful hint: If you know your cooker cooks fast–or you think chicken breasts cooked in the slow cooker tend to be dry–check after 2 hours. Some cookers, especially larger models that are filled less than halfway, do their work far quicker than many recipes stipulate.) Remove the chicken to a bowl, allow to cool for a few minutes, and then use two forks to coarsely shred. If you’d like to reduce the sauce (it will be a thin sauce), turn the cooker to high (or simmer mode if you have it), and cook with the lid off to reduce to your liking. Stir the shredded chicken back into the sauce or ladle the desired amount of sauce into the shredded chicken in a bowl. Season with with salt, if needed, and a squeeze of lime juice, if desired. Serve in bowls or in tortillas with toppings of choice.