Cut the steak into 4 equal pieces and season generously with salt and pepper.
Press the ‘saute’ button and add the oil to the Instant Pot. Working in batches, sear the steak until a deep brown crust forms on both sides, 3 to 4 minutes per side. Transfer to a clean plate and set aside.
Add the onions, garlic, oregano, thyme, smoked paprika, cumin, and cinnamon. Stir until well combined. Add the apple cider vinegar and broth and stir, scraping up any browned bits on the bottom of the pot.
Click the ‘cancel’ button to turn off the ‘saute’ function. Add the lemon zest and nestle in the browned beef. Place the lid on top of the Instant Pot and turn the valve so that it is sealed. Press the ‘manual’ button, then set the time to 45 minutes.
When the cooking time is complete, manually release the pressure by carefully turning the valve to vent. Allow all of the steam to release (this takes a few minutes) before carefully opening the Instant Pot. Use two forks to shred the beef.
Serve the beef over cooked rice or cauliflower rice or tucked into pitas and garnish as desired.