Season chicken with 1 1/4 teaspoon salt and 3/4 teaspoon pepper. Heat canola oil; working in batches, add chicken and cook until golden brown, about 3-4 minutes per side; set aside.
Add onion, and cook, stirring frequently, until translucent, about 2-3 minutes. Stir in garlic, chipotle chili powder, cumin and oregano until fragrant, about 1 minute.
Stir in salsa and beer, scraping any browned bits from the bottom of the pot.
Return chicken to the pot and gently toss to combine.
Select manual setting; adjust pressure to high, and set time for 8 minutes for chicken thighs or 13 minutes for chicken breasts. When finished cooking, quick-release pressure according to manufacturer’s directions.
Remove chicken from the Instant Pot® and shred using two forks; season with salt and pepper, to taste, if needed.
Serve immediately in tortillas with desired toppings.
Notes
*Chicken stock can be used for Mexican beer as a non-alcoholic substitute.