In a bowl take chicken, add salt, 1 teaspoon garlic,1 teaspoon red chili, 1 teaspoon lemongrass, and fish sauce.
Set the instant pot on the SAUTE function, let it heat up.
Add in the remaining garlic, lemongrass, and chilies. Sauté it for a few seconds until fragrant.
Next add in the marinated chicken and cook until the chicken turns a little brown from pink.
Add ¼ cup water and brown sugar. Deglaze the pot by stirring properly so no food is stuck to the bottom of the pot.
Add in the onion cubes on top.
CANCEL the SAUTE button. Select the PRESSURE COOK button on HIGH PRESSURE for 6 minutes. (Make sure the valve is in the SEALING position).
Once the pressure-cooking cycle is over. quick release pressure by manually moving the valve from SEALING to VENTING position.
Open the lid carefully and select the CANCEL button.
Serve hot with steamed rice garnished with chopped red chilis.
NOTE: You can store the chili in an airtight container for 4 days in the refrigerator or around 3 months in the freezer.