First make the marinade; Combine the chipotle pepper, onion, lime juice, tomato paste, garlic cloves, vinegar, cumin, salt, and oregano in a food processor, or blender. Process until smooth.
Trim any excess fat off of roast, and cut into 2 or 3-inch pieces.
Using the saute button on your Instant Pot, add the oil and brown the meat, in batches on all sides (approx 5 minutes). Add the sauce from the blender, chicken stock, and bay leaves.
Cover, and cook on high pressure for 60 minutes. Let pressure release naturally, about 15 minutes.
Remove the beef from the liquid and shred with two forks. Return to IP, and season to taste with any additional salt and pepper, if needed. Garnish with cilantro.