Brown the mince in a little oil over high heat. Add the onion, garlic and taco seasoning and fry, stirring occasionally, for 5-10 minutes. Add the tomato, a little water and cook until the moisture has evaporated. Set aside to cool.
Pop a layer of nachos in a baking dish. Add a layer of chilli. Add beans, salsa and cheese. Repeat until the dish is full. Top with extra cheese. Bake for 30 minutes at 180°C. Top with mustard, onion and roquitos.