In a medium bowl, stir together the flour, cornstarch, 2 tsp salt, 1 tsp black pepper, granulated garlic, and cayenne. In another medium bowl, whisk together the egg and beer.
Set a wire rack on a rimmed baking sheet. Pat the fish dry with a paper towel. Cut into strips about 3 inches (7.5 cm) long and 1 inch (2.5 cm) wide. Working with a few strips at a time, coat the fish in the flour mixture, shaking off the excess. Dip in the egg mixture, letting the excess drip off. Return the fish to the flour mixture and coat well, shaking off the excess. Place the coated fish on the wire rack as you go.
Coat the Instant Pot air fryer basket with canola oil spray. Working in batches, coat the fish strips generously with canola oil and arrange a single layer of strips in the basket, making sure they don’t touch. Insert the basket into the pot and attach the air fryer lid. Press the Air Fry button and set the cook time for 15 minutes at 375°F (190°C), then press Start. Flip the fish strips when prompted, coating again with oil.
Meanwhile, make the lime crema: In a small bowl, stir together the sour cream, half the lime juice, 1/4 tsp salt, and a few grindings of black pepper. Taste and adjust the seasoning as needed.
To make the pico de gallo, in a small bowl, stir together the tomatoes, onion, chile, cilantro, lime juice, and 1/2 tsp salt. Taste and adjust the seasoning as needed.
When the cooking time is up, use tongs to carefully transfer the fish to a plate and season to taste with salt and black pepper. Repeat to cook the remaining batches.
Spread some lime crema on the tortillas and top with the fish, cabbage, pico de gallo, and cilantro. Serve with lime wedges alongside.