Cut the chicken thighs into 2-3 inch chunks to ensure even cooking and flavor absorption.
Set the Instant Pot to sauté and heat the vegetable or canola oil. Brown the chicken chunks in batches for 5-7 minutes, then remove and set aside.
Add minced ginger and garlic to the pot and stir for about 30 seconds until fragrant, being careful not to burn them.
Add red chili flakes, rice vinegar, soy sauce, hoisin sauce, water, and brown sugar to the pot. Stir well, scraping up browned bits from the bottom.
Return the browned chicken to the pot, making sure it is submerged in the sauce. Close the lid, set the valve to sealing, and cook on high pressure for 10 minutes.
Perform a quick release by carefully turning the valve to venting once the cooking time is complete. Open the lid when pressure is fully released.
Mix cornstarch with 3 tablespoons of water in a small bowl to create a slurry. Turn the pot back to sauté and stir in the slurry. Cook until the sauce thickens to your liking.
Serve the General Tso Chicken over steamed rice or noodles. Garnish with red pepper flakes, sesame seeds, and chopped green onions.