Add olive oil to Instant Pot® and select the Sauté function. Set to high and once the display reads “hot,” add red onion, bell peppers, and Poblano pepper. Season with salt and black pepper, to taste, and cook, stirring continually, until the onion and peppers are crisp-tender and develop a bit of color, approximately 4-5 minutes. Switch unit to “off” and transfer veggies to a bowl. Set aside.