Place the beef chuck roast in the crockpot. No need to trim much — just make sure it fits.
Add the broth, soy sauce or coconut aminos, minced garlic, sliced onion, lime juice, chili powder, salt, and pepper.
Stir gently or spoon some liquid over the top so the beef gets coated.
Set the crockpot to low and let it cook for about 8 hours, or on high for 4–5 hours if you’re short on time.
When it’s done, the beef should be soft enough to shred easily. Use two forks and pull it apart right in the pot.
Stir the shredded beef back into the juices. Let it sit on “warm” for 10–15 minutes so it soaks everything up.
Rinse and separate your lettuce leaves while the beef rests.
Spoon some of the shredded beef into each lettuce leaf.
Add any toppings you like avocado, cilantro, lime juice, or a bit of hot sauce.
Fold, bite, and enjoy.