Select Saute/Browning and allow Instant Pot to fully heat.
Add oil, onions and peppers and saute for 3 minutes.
Add ground beef, enchilada sauce, taco seasoning and salt and mix into onions and peppers, making sure to break up the beef. Scrape the bottom of the pot to loosen anything that might have stuck.
Mix in ketchup, beans and Rotel (or tomatoes).
Lock on lid and close pressure valve. Cook at high pressure for 4 minutes. When beep sounds, wait 10 minutes and then release the rest of the pressure.
Open lid and stir in Maseca. If there is excessive liquid (fattier meat will give off more liquid) simmer to reduce. Stir in shredded cheese and serve on toasted hamburger buns or brioche buns. Top with sour cream and more shredded cheese.
Tomatoes can be added in with the cheese at the end, if desired.