Mix everything except liquid.
Slowly add enough liquid until it's a playdoh consistency–soft and easy to mold, but doesn't stick to your hands. If it's too wet, add more masa or if it's too crumble (too dry), add more liquid but a little at a time until you get it just right.
You can use any filling you want. I used some leftover pulled pork, some green enchilada sauce, and a small slice of Monterey Jack cheese in each one.
Take a moistened corn husk, place some masa on the husk, and pat it down into an approximate rectangle. If you are making a ton at a time, you might want to invest in a Tamale spreader. It spreads the masa evenly on the corn husk every time so you can quickly do a large quantity.
Add your filling. Pull each side of the husk toward the center, so the dough covers the filling. Then finish wrapping with the husk, and fold the small pointy side up.
Place tamales, folded side down and open end up, either on the trivet or in a steamer basket. I actually took the insert out of the IP, left the trivet in, and put the insert on its side so I could stack the tamales in without them falling over.
Once it was mostly filled, I could right the insert and the tamales stayed standing up. Then I just put the insert back in the pressure cooker. I added 2 cups water along the side. Now close the pressure cooker. Make sure the valve on the top is set to "sealing."
Press manual (should be high pressure), adjust the setting to 18 minutes.
It will take about 15 minutes for it to come to pressure so don't be surprised if it doesn't start right away.
After the 18 minutes is up, I let it sit (natural pressure release) for 10 minutes. The machine will start to count for you.
Then released the rest of the pressure (quick release) by poking the valve with a wooden spoon to switch from sealing to "venting". This will release any pressure that is still built up in the machine.
To eat, you unwrap the tamale and discard the husks (they are only used in the cooking process).