Season the short ribs with salt and pepper. Add olive oil to the Instant Pot. Using the display panel select the SAUTE function, then START.
When oil gets hot, brown the meat on two sides, 4 minutes per side. Meat will not be cooked through. Do not crowd the pot--you may have to work in batches. Transfer browned ribs to a shallow dish and cover loosely with foil.
Add onions and peppers to the pot and saute until soft, 3-4 minutes. Add chili powder, cumin and garlic, then cook and stir one minute more.
Add tequila to the pot and deglaze by using a wooden spoon to scrape the brown bits from the bottom of the pot. Add beef broth and stir. Put the ribs back into the pot, turning once to coat. Turn the pot off by selecting CANCEL, then secure the Pressure Cooking Lid.
Using the display panel select the PRESSURE COOK function. Adjust the time to 45 minutes, then select START.
When the time is up, let the pressure naturally release for 15 minutes, then quick-release the remaining pressure. Carefully remove the ribs from the pot to a cutting board and cover loosely with foil.
Select CANCEL, then strain the pot juices and discard the solids. Using a wide spoon or a fat separator, return 2 tbsp cooking fat to the pot. Skim and discard the remaining fat. If needed, add additional beef broth (ore water) to the remaining cooking liquid to equal 1 1/4 cup, then set aside.
Select SAUTE function, then START. Sprinkle flour, 1/2 tsp kosher salt and 1/4 tsp pepper into the pot and whisk to combine. Add cooking liquid all at once and whisk to combine. Cook and stir until thickened and bubbly, then cook and stir one minute more. Pour sauce into a measuring cup or bowl and set aside. Rinse the pot.
Shred beef with two forks, discarding bones, visible fat and any gristle.
Divide cheese and half the beef among the tortillas, spreading evenly on one side of the tortilla, then folding over to close.
Place two of the folded quesadillas in the bottom of the Air Fryer Basket. Insert the Broil Tray and place the remaining folded quesadillas on the Broil Tray. Place the Steam Rack on top to keep the tortillas from blowing around.
Place the Air Fryer Basket on its base and lower into the pot. Secure the Air Fryer Lid onto the Instant Pot. Using the display panel, select the AIR FRY function. Adjust the temperature to 400°F and the time to 8 minutes, then select START.
When display reads “Turn Food”, flip and move the top quesadillas to the bottom position and flip and move the bottom quesadillas to the top position. When program is complete, cut each quesadilla into 3-4 triangles.
Serve the quesadillas topped with remaining beef, a dollop of sour cream (optional) and drizzled with sauce, with additional sauce on the side for dipping. Top with chopped cilantro (optional).