In a large skillet over medium heat, cook beef and onion, breaking up the beef, until beef is nearly browned. Stir in the garlic and cook until beef is fully browned. Drain fat and discard.
Stir in tomato sauce, Rotel, hot sauce, taco seasoning, and black pepper. Simmer, uncovered, for 5 minutes or until thoroughly warmed.
In a small bowl, toss cheese with flour. Add cheese to beef mixture, a little at a time, stirring just until melted. Transfer to a small crockpot or fondue pot to keep warm.
Serve hot or warm, with sturdy tortilla chips. If desired, offer taco toppings such as sour cream, sliced green onions, chopped tomatoes, diced jalapeno, avocado or guacamole, etc. alongside.
