Preheat oven to 350°F.
Add beef chuck roast to an oven-safe dish with a lid.
Season both sides of the beef with salt, pepper, and taco seasoning.
Add sliced yellow onion, garlic cloves, and fresh oregano or thyme.
Pour in 17 oz of beef broth.
Cover and bake at 350°F for 3 hours.
Remove from oven, shred the beef using two forks, and mix well with the drippings.
Return the shredded beef to the oven, uncovered, at 425°F for 45 mins to 1 hour.
In a small food processor, blend the Greek yogurt, salsa, lime juice, and salt.
Serve the shredded beef with the yogurt-salsa sauce, low-carb rice, avocado, and red onion.
