In a large skillet over medium-high heat, brown the ground beef with the diced onion until the beef is fully cooked and onions are translucent.
Add minced garlic to the skillet and cook for an additional 1 minute until fragrant.
Drain excess grease from the skillet and stir in the taco seasoning and beef broth.
In the slow cooker, layer one-third of the tortilla strips on the bottom.
Top with one-third of the beef mixture, followed by one-third of the beans, corn, and tomatoes.
Repeat the layering process two more times, finishing with the remaining beef and vegetable mixture.
Cover and cook on low for 4 hours or on high for 2 hours.
15 minutes before serving, sprinkle the shredded cheese and black olives over the top, then cover again until the cheese is melted.
Serve warm with optional garnishes like sour cream or cilantro.