Set the Instant Pot on SAUTE function and set it on NORMAL heat settings.
Add oil and thrown in the chopped garlic when the oil becomes moderately hot. Saute for just 30 seconds.
CANCEL the SAUTE function and add in the liquid. De-glaze the pot.
Now, add the spaghetti noodles in a bird nest patter or a zig zag pattern. Avoid dumping them all at once. Once, you are done gently tap the spaghetti noodles with the help of your spatula so that they get one coat of the liquid. DO NOT STIR.
Layer the sliced veggies on top of the noodles. If you prefer crisp crunchy veggies do not add them now. Do not STIR anything in the pot.
Cover the lid of the Instant Pot and seal the valve. PRESSURE COOK on HIGH for 4 minutes for al dente noodles that won't fall apart and 6 minutes for softer noodles.
Once the pressure cooking cycle is over wait for about 3 minutes of Natural Pressure Release and than release the rest of the pressure manually by moving the valve from the SEALING to the VENTING position. Open the lid of the pot carefully.
You'll be left with little liquid. and softer veggies Don't worry the cooked noodles will absorb the liquid beautifully once you begin the process of de-tangling the noodles.
CANCEL the PRESSURE COOK function and de-tangle the noodles gently with the help of a fork and in the process mix in the cooked veggies with the noodles.
Now, set the Instant Pot on SAUTE and keep it at LOW.
Add all the sauce ingredients mentioned above in the "For the Sauce" section. Add the brown sugar in the light soy sauce and mix it to incorporate first and than add it to the pot. This will help to dissolve the sugar fast.
Toss the noodles in the sauces for about 2-3 mins. Turn off the Instant Pot and garnish with the scallions and toasted sesame seeds. Serve hot with more Chili garlic Sauce and red pepper flakes if you prefer really spicy food. Enjoy!