1Cut the beef in half. Place in the pressure cooker or slow cooker.
2In a small bowl, whisk together the brown sugar, tamari, garlic, beef broth, ginger, rice vinegar, and sesame oil. Pour the mixture over the beef.
3INSTANT POT: Press the Manual or Pressure Cook button (high pressure) and secure the lid, making sure the valve is set to sealing. Cook at least 15 minutes. Allow the pressure to release naturally for at least 25 minutes. SLOW COOKER: Cover and cook on low for 8–12 hours, until tender.
4Remove the lid and shred the beef. Return beef to the cooking juices.
5In a bowl, toss all cabbage slaw ingredients together.
6Prepare sriracha sour cream by stirring together the sour cream and Sriracha.
7Prepare uncooked tortillas according to package directions. Scoop some meat onto each tortilla. Top with cabbage slaw, sriracha sour cream, cilantro, and diced avocado. Splash a bit of rice vinegar over the top, fold up, and enjoy.
Notes
Timing shown is for the Instant Pot method (cook 60 min + 25 min natural release). For slow cooker, cook on low 8–12 hours. Nutrition is for the beef only (per serving).