You can either cook your ground beef in the Instant Pot or a skillet - if cooking in the Instant Pot, you may want to clean it in between cooking the meat and and making the taco casserole. However, the IP gets hot so I prefer to cook the meat in a skillet and just do the taco casserole in the Instant Pot. (This is also great for prep-ahead days.)
To make the taco meat, add the ground beef to a large skillet over medium heat.
Stir and break up the ground beef while cooking for 3-5 minutes, until fully browned.
Drain off any excess fat and then add in the taco seasoning, tomatoes and black beans. Stir together and allow to cook for 3 additional minutes.
To avoid a "BURN" error, add 1 cup of water to the inner liner and then place the trivet that came with your pot in the bottom of the pan before layering the ingredients.
For the taco casserole, spread 3 Tablespoons or so of refried bean paste onto a tortilla and place it bean side-up in the Instant Pot.
Top with 1 cup of the ground beef mixture, then 1 cup of cheese. Repeat for 1-2 additional layers and then add a generous handful of cheese on top of a final tortilla.
Place the lid on your IP and seal. Cook for 5 minutes on Manual pressure - you can natural or quick release but natural release may dry out the cheese slightly.