Set the saute function in a 6-quart electric pressure cooker for 8 minutes.
Add the olive oil, onions, ¼ teaspoon salt, and saute for 8 minutes, stirring occasionally.
Add the tomato sauce, water, cumin, garlic powder, and chicken, stirring to combine.
Secure the lid, select the manual setting, and set it to high pressure for 15 minutes for fresh chicken, or 20 for frozen. If using frozen chicken, make sure it’s spread in an even layer, without sticking together.
When the pressure cooker timer is done, quick release the pressure.
Remove the chicken, and shred or chop into bite sized pieces. Add back to the pressure cooker, stirring to combine. Taste, adding lime juice, hot sauce (if using), and additional salt or pepper if desired.