Preheat oven to 350°F. Add water to the dutch oven.
Arrange peppers so that they're bottom down in the water and bring the water to a boil. Cover and steam the peppers for 2-3 minutes or until just barely softened. Remove peppers to a casserole dish.
Meanwhile, in a large, deep skillet, heat the oil over medium high heat. Once the oil is hot, brown the ground beef with the diced onion and garlic, until fully browned, approximately 5-7 minutes. Add taco seasoning and water as indicated on the package. Reduce heat to low and simmer for 3 minutes stirring frequently.
Add cauliflower rice, rotel, and remaining seasonings to ground beef mixture. Mix well to fully incorporate the new ingredients. Simmer until the rotel is fully heated, about 2-3 minutes. Remove from heat and stir in half of the cheese.
Divide the mixture evenly between the peppers. Top with remaining cheese, tomato, and green onion. Cover the casserole dish and peppers with foil. You may need to create a tent with the foil so that the toppings don't stick to it. Bake for 15 minutes.
After 15 minutes of baking, uncover the peppers and bake uncovered for an additional 10 minutes or until filling is fully heated through, peppers are softened, and cheese is melted. Allow to cool for 5 minutes.
Serve and enjoy.