Thaw the cauliflower rice completely and drain the Ro-Tel tomatoes.

In a large skillet, heat olive oil over medium heat and sauté the chopped onion until soft and translucent.

Stir in thawed cauliflower rice and cook for an additional 3 to 4 minutes, then sprinkle in chopped green onions.

Add another tablespoon of olive oil and ground beef to the same pan, browning until no longer pink.

Stir in taco seasoning, mix well, and heat with the drained Ro-Tel tomatoes for 2 to 3 minutes.

Combine the seasoned beef mixture with the cooked cauliflower rice, adding 2 cups of Mexican blend cheese until melted.

Preheat the oven to 375°F (190°C). Transfer the mixture into a greased casserole dish, top with remaining cheese, and bake for 30 minutes.

Let the casserole sit for a few minutes before serving with sour cream, salsa, and lime wedges.