This is a remarkably easy recipe, especially considering that it results in a tender chicken with a homemade, not store-bought, salsa verde. It's excellent served over rice, as a filling and sauce for enchiladas, or in tacos with all your favorite fixings.
Heat the olive oil in the IP on the "Saute" setting. Add the sliced onion and saute until just tender, 6 minutes. Add the garlic, jalapeno, tomatillos, lime juice, salt, and chicken. Stir well. Secure the IP lid and set to "Manual" (high) for 12 minutes with the vent closed.
Leave it to release naturally for 10 minutes. Release any remaining steam with care and remove the lid. Use tongs to lift the chicken pieces from the pot into a medium bowl (being sure all the other ingredients remain in the IP).
Add the cilantro to the IP and use an immersion blender to blend everything into a smooth sauce (or transfer to a conventional blender and blend until smooth). It will thicken slightly as it cools and yields quite a bit of sauce. Pour over the chicken and stir.
Serve as desired, such as over cooked rice, in tacos or burritos, or to make enchiladas.