To make the short ribs, turn your electric pressure cooker to Saute and add oil.
Once hot, brown short ribs on all sides, about 3 to 4 minutes per side. Remove from insert and place on a plate.
Add peppers, onion, and garlic to the insert. Stir frequently, cooking until onion is softened, about 2 to 3 minutes.
Add lime juice, taco seasoning, salt, and broth, stirring until combined. Be sure to use a wooden spoon to scrape up any browned bits that stuck to the bottom.
Return ribs back to the insert. Cover and lock lid in place.
Set pressure cooker to Manual and cook for 50 minutes on High pressure. Once done, let pressure naturally release for 10 minutes.
Remove short ribs and shred with two forks on a cutting board. Note at this point you can place the short ribs in an airtight container for up to 2 days in the refrigerator, if you want to make the pie at a later point.
For the Sauce:
To make the sauce, heat oil in a large skillet over medium-high heat. Add onions and sauté for 5 to 10 minutes, stirring frequently until browned.
Reduce heat to medium and stir in chili powder, cumin, oregano, cayenne pepper, salt, and garlic. Cook for 2 to 3 minutes, until fragrant.
Stir in chicken broth and tomatoes. Bring to a simmer, cooking for 5 to 10 minutes until the sauce is deepened in color.
Add sauce to a blender or food processor, processing until smooth. Set aside.
Assemble the Pie:
To assemble the pie, start by preheating the oven to 375˚F.
Dip 5 small tortillas into the sauce. Layer them in the bottom of a 9-inch ovenproof skillet.
Top with a scoop of short ribs, a handful of cheese, and 3/4 cup sauce. Repeat this set of layers.
Top with one more layer of dipped tortillas, remaining sauce, and cheese.
Cover with foil, making sure it doesn’t touch the top of the pie.
Bake for 20 to 30 minutes, until cheese is melted, and sauce is bubbly.