Choose the sauté button on the Instant Pot and add the vegetable oil. When it displays “hot,” add the ground beef and chopped onion. Cook, stirring frequently, and the beef is browned and no longer pink.
Add the taco seasoning, ranch dressing, 1/2 teaspoon of salt, the pepper, cumin, tomatoes, beef stock, beans, and corn.
Secure the lid and make sure the steam release valve is turned to “sealing.” Choose pressure cook, high pressure, and set the time for 10 minutes. When the time is up, let the pressure release naturally for 15 minutes and then carefully turn the steam release valve to “venting” to release the remaining pressure. If your pressure cooker or model is different, follow the manufacturer’s directions for steam release.
Ladle the soup into bowls and top with tortilla chips or strips and your favorite garnishes.