In a large skillet over medium heat, add oil. Once hot, toss in diced onion and bell pepper, cooking until onions are translucent and peppers are tender.

Add ground beef to the skillet, breaking it apart. Cook until browned and no longer pink for 5-7 minutes. Stir in taco seasoning and water.

Mix in frozen cauliflower rice and diced tomatoes. Stir well and let simmer on low for about 10 minutes.

Sprinkle shredded cheddar cheese over the top. Cover skillet and cook for an additional 2-3 minutes over low heat until the cheese is melted.

Remove from heat and serve immediately with optional garnishes like avocado or sour cream.