Heat a skillet over medium-high heat and add the beef. Cook, breaking it apart with a spoon, until browned, 8-10 minutes. Stir in the taco seasoning and a small splash of water, then simmer for 1-2 minutes. Turn off the heat and set aside.

In a small bowl, mix the Greek yogurt, green chilies, lime juice, and a pinch of salt.

Add chopped romaine to a dish and top with the beef, yogurt mixture, cheese, and red onion. Serve.