Make the marinade: Whisk achiote paste, orange/lime juice, oil, garlic, oregano, cumin, salt, cloves, and broth until smooth.
Load the pot: Place pork chunks and bay leaf in the Instant Pot. Pour marinade over, turning meat to coat.
Pressure-cook: Seal lid. Set Manual | High | 45 min. Allow 10 min natural release, then quick-vent the rest. Remove bay leaf.
Shred & reduce: Transfer pork to a bowl; shred with two forks. Switch pot to Sauté | High and simmer juices 5 min until slightly thick. Return pulled pork; toss to glaze. Adjust salt.
Serve taco-bar style: Set out lettuce leaves, pork, and garnishes. Build tacos: lettuce cup → pork → pickled onion → avocado → cilantro → lime squeeze.