Select Saute and add oil to the Instant Pot. When oil is hot, add the onion, carrots, and celery, and cook, stirring occasionally, until tender, about 5 minutes.
Add poblano pepper and garlic. Cook for 1 more minute.
Add half of the chicken broth, thyme, salt, pepper, red pepper flakes, and parsley to the pot.
Put the steamer basket in the pressure cooker pot. Add the diced potatoes.
Lock the lid in place, select Manual and adjust to high pressure cooking. Set time to cook for 4 minutes. When timer beeps, turn off pressure cooker, allow natural release for 5 minutes, then do a quick pressure release. Carefully remove potatoes and steamer basket from the pressure cooking pot.
In a small bowl, dissolve cornstarch in 3 tablespoons water. Select Simmer and add cornstarch mixture to the pot stirring constantly until mixture thickens.
Gradually whisk in the remaining chicken broth. Stir in half and half, corn, and potatoes; heat through but do not bring to a boil.
Add a dash of hot sauce, if desired. Garnish with fresh parsley. Enjoy!