1. Trim of any excess fat from the beef tongue anf place in a 5 quart pressure cooker. Add onion, garlic, jalapeño, bay leaves, peppercorns, salt and just enough water to come 1/2 inch below the fill line. Secure and lock the lid and heat to high. When the safety valve locks and the cooker begins to hiss and let out steam, turn heat down to medium/low. Set timer for 1 hour, 30 minutes.
2. When timer is up, carefully move the pressure cooker off of the burner to cooler side. When safety valve releases and unlocks, remove the lid. Remove beef tongue and transfer to cutting board, let cool slightly. Remove outer skin and excess fat from beef tongue. Slice or chop the beef to the size you like. Serve with warm corn tortillas, salsa, cilantro, diced onion, lime and avocado slices. You can serve it as it for tacos or you can prepare a guisado de lengua.