Set the Instant Pot on SAUTE and keep it on NORMAL. Add oil.
In the meantime coat the cubed chicken pieces with 1 tbsp light soy sauce or Tamari.
When the oil becomes moderately hot gently release the cubed chicken pieces and saute them until opaque from all sides. It should take you about 2 minutes.
Add the veggies and give everything a good stir.
CANCEL the SAUTE function. Pour the water or chicken broth and de-glaze the pot very well so that there are absolutely no bits and crumbs stuck at the bottom of the pot.
Snap the ramen blocks into small pieces (refer the step by step pictures above) discard the flavor packets.
Add the broken ramen into the Instant Pot and give everything a good mix. Ensure that all the ramen pieces get a good coat of liquid. Do this by gently pressing the ramen with your spatula, turn them and press them. Repeat the process. They do not have to be submerged in the liquid, just a good coat should be fine.
Close the lid of the Instant Pot. PRESSURE COOK on HIGH for 1 minute.
When the pressure cooking cycle is over the Instant Pot will begin to beep. Immediately do a QUICK PRESSURE RELEASE (QPR) by moving the valve from the SEALING to the VENTING position. Open the lid carefully.
Turn off the Instant Pot. Add the soy sauce and the sesame oil and immediately fluff the ramen noodles with the help of a fork. Do not rush do it gently. This will help to de-tangle the noodles and also help to coat the noodles with the sauce & the sesame oil.
A few ramen noodles might appear a little under-cooked when you open the Instant Pot. Do not worry, they will be fully cooked once you mix the sauce and fluff the noodles. The trapped residual heat will cook them completely. Do not be tempted to pressure cook them again.
Allow the ramen noodles to rest for 5 mins, this helps the noodles to nicely absorb the sauce. Mix in the chopped green onion.
Once, you are done fluffing the noodles and mixing in the sauce bring out the steel insert of the instant pot and keep it on the counter top. Or you may also spoon out the cooked ramen into a separate plate. This will prevent the cooked ramen from getting over cooked and mushy from the residual heat of the Instant Pot. The Instant Pot base gradually cools down even after unplugging the machine.