In a medium bowl or large measuring cup, whisk together the soy sauce, honey, rice vinegar, water, garlic, ginger, and red pepper flakes. Place the chicken thighs in the bottom of the pressure cooker insert, pouring a little bit of sauce between the layers and the rest over the top.
Seal the lid of the Instant Pot according to the owner's manual and cook on HIGH pressure for 10 minutes.
When the timer is done, allow the pressure to release naturally for 5 minutes, then carefully vent to release the remaining pressure (consult your owner's manual for more specific instructions).
Open the lid, remove the chicken thighs to a plate, and set the Instant Pot to SAUTE. In a small bowl, whisk together the cornstarch and water until completely dissolved. Once the sauce starts bubbling, slowly pour in the cornstarch slurry while whisking the sauce. Allow to bubble and cook for a minute or two, stirring occasionally, until the sauce is thickened. Cancel the SAUTE function and add the chicken back to the sauce. Serve the sauce with the chicken thighs over rice, or shred the chicken thighs into the sauce and serve on buns.
For frozen thighs, cook on HIGH for 13 minutes and allow the pressure to release for 10 minutes.
You may make this recipe with chicken breasts instead. Cook on HIGH for 10 minutes and then release pressure for 10 minutes.
If you prefer using bone-in, skin-on chicken things, you will want to crisp the skin as a first step (unless you plan on removing the skin before eating). You can brown the thighs in a tablespoon or two of oil (directly in the Instant Pot insert using the SAUTE function) for 1-2 minutes per side before proceeding with the recipe. After browning, just be sure to scrape all of the dark bits from the bottom of the pot (you can add a little water to deglaze the pot) before adding back the chicken and sauce. Otherwise, the Instant Pot may give you a burn warning after sealed.