Place chicken breasts in pressure cooker. Sprinkle chicken breast with salt, cumin and oregano.
Add onion and diced green chilis on top of chicken breast.
Place lid on pressure cooker, set to high pressure and cook for 30 minutes. Quick release, then open when pressure subsides. Shred chicken and use as desired.
Slow Cooker
Place chicken breasts in slow cooker. Sprinkle chicken breast with salt, cumin and oregano.
Add onion and diced green chilis on top of chicken breast.
Set slow cooker to low for 8 hours or high for 4 hours. When slow cooker is done, shred chicken and use as desired.