PREHEAT oven grill to high. Set aside a large casserole/baking dish (if you do not have an oven-proof fry-pan).
Heat a little oil in a large fry-pan (preferably oven-proof) on high heat. Cook beef mince and onion, breaking up mince with a wooden spoon as it cooks, for 7–8 minutes, until browned. Add nacho spice mix and chilli flakes/powder (if using) and cook a further 1 minute, until fragrant.
Stir through beans, tomato paste, tomatoes, corn, carrot and beef stock. Bring to a simmer then reduce heat to low and simmer, stirring occasionally, for 9–12 minutes, until thickened. Season to taste with salt and pepper.
While sauce is simmering, prepare the rest of the meal. In a small bowl, mix sour cream and tomato sauce together and set aside. Place lettuce and carrot in a serving bowl.
Sprinkle cheese over mince and place whole pan under grill for about 6 minutes, until cheese is bubbling and golden. If you don’t have an oven-proof fry-pan, transfer mixture to an oven-proof dish before adding cheese.
TO SERVE place beef nacho sauce, corn chips, tomato sour cream, lettuce and carrot in the middle of the table for everyone to help themselves.
To make nacho spice mix, combine ½ teaspoon each of smoked paprika, dried oregano, onion powder and ¼ teaspoon ground cumin and ground coriander.