Cut the onions and peppers into squares and chop the chillies.
Put the soy sauce, red chilli sauce, tomato ketchup, brown sugar, white vinegar and ground black pepper in a bowl. Add ½ cup water and whisk lightly with a fork or spoon to combine into a sauce.
Mince the ginger and garlic.
Cut the chicken into bite-sized pieces.
Cooking
Switch on the instant pot and press saute. Add the oil and wait for the display panel to show HOT. Add the minced ginger and garlic and fry for a few seconds in the hot oil.
Add the sauce (step 2 of prep) and the chicken. Stir through to mix the two and cancel saute.
Secure the lid and press the poultry button. The timer will show 15 minutes. Make sure the steam release handle is sealed. When the pot beeps, wait for 10 minutes, then release pressure by turning the steam release handle to venting.
Open the pot and switch back to saute mode, Add the vegetables (onions, red and green peppers and green Serrano chillies). Cook for 3-4 minutes or until the vegetables are slightly soft but still crunchy.
Add the cornflour dissolved in 4 tablespoons water and cook for 1 minute more. The sauce will thicken immediately and become glossy. Cancel saute and take out the chilli chicken in a bowl. Garnish with chopped spring onions and serve warm with rice or noodles.
Notes
Use a neutral cooking oil like canola.
Ginger and garlic pastes are available in jars in most supermarkets.
Don't over cook the vegetables. You don't want them raw but you do want a slight crunch.
If the sauce becomes very thick after adding the cornflour, thin it with a little water.