Rinse the tomatillos and place in a large stock pot.
Add serranos, garlic, and onion to the pot.
Cover with water.
Bring to a boil and cook for 7 minutes.
Place tomatillos, onion, garlic, and serranos to a blender.
Add cilantro and salt to the blender.
Blend until smooth. Set aside until ready to use.
How to Assemble Tamales:
Soak the corn husks in a warm water for 20 minutes.
Drain water. Shake off any excess water.
Smear a thin layer of prepared masa on each corn husk.
To the middle of the masa layer, add a tablespoon of the chicken.
Add a spoonful of salsa verde over the chicken.
Fold one side of the corn husk in and over the chicken.
Fold the other side in.
Fold the pointy top to the center of the tamale.
Stand upright and set aside.
Repeat until there are no more corn husks left.
Place the steam rack crate on the bottom of the Instant Pot.
Add 1 cup of water.
Place all the uncooked tamales on the rack.
Open side up.
Lock the lid in place.
Turn the valve to "SEALING."
Set the Instant Pot to pressure cook at high pressure 35 minutes.
When done, turn the valve to "venting."
It will release any leftover steam.
Let stand for 10 minutes.
Remove the lid very carefully.
The tamales are ready when they peel away from the corn husk easily.