Using a large skillet coated with nonstick cooking spray, cook the meat, onion, and garlic over medium heat, stirring to crumble. Cook 5 to 7 minutes or until the meat is done. Next, drain any excess fat, and then add the cumin, salt, pepper, and rice.
Remove from the heat, and let cool. In a large bowl, mix the lettuce, tomatoes, cheese, red onion, and the rice mixture. Then, in a separate bowl, combine together the sour cream and salsa, and toss lightly with the lettuce-rice mixture. Serve immediately, with extra salsa and chips, if desired.