Turn on the instant pot to SAUTE mode.  Add the oil to the pot.  Once the screen shows HOT, add the chopped onions and cook until translucent and then add minced garlic to it.  Cook it for a 30-40 seconds.

Now add the enchilada sauce and water along with the chili powder, cumin, diced tomatoes and taco seasoning(if using).  Mix it well and add dry pasta shells to it.  Make sure the pasta shells are covered under the liquid.

Close the lid and set the valve to SEALED position.  Press MANUAL and set it for 4 mins.  Once it beeps, release the pressure right away (QPR).  The sauce should be a little watery consistency. Add a little bit of corn and black beans to it and mix it well.

Sprinkle cheese, corn and black beans on top.   Close the lid for a couple of mins and this will help the cheese to melt.  Your Tex Mex Pasta is ready.

Garnish it with cilantro, avocado, jalapeños, and a dollop of sour cream.  If you want you can also put some salsa. Sprinkle lime juice if you want.

Serve hot and enjoy the flavors.