Place a trivet or steam basket inside the pressure cooker pot.
Add one cup of water or the minimum liquid requirement for your pressure cooker. I used a 6 quarts pressure cooker.
Add frozen ground beef on top of the trivet, no need to break it down. If you have longer pieces that don't fit, break them in 2 so you can place them on the trivet.
Place the lid and lock it, make sure to close the sealing valve.
Pressure cook on high pressure for 20 minutes for 1lb and 23 minutes for 2lbs of meat.
Once the program is done, do a 5-minute Natural Pressure Release, after that open the valve to release the remaining pressure.
Using an instant-read kitchen thermometer, take the temperature of your meat, it should be about 160F-165F.
Poke the center and see if it's still raw, if the meat is still undercooked, transfer it to a bowl, and in the meantime discard the liquid from the inner pot.
Select sauté mode, once hot add one tablespoon of oil, add the beef, break it down with a wooden spoon, and brown it until done.
Season with salt, pepper, and taco seasoning if using. If the beef seems a bit dry, add 1 tablespoon of warm beef broth and mix.
Serve or use in other recipes when ready.