Heat a little oil in a pan and fry the onion, peppers and garlic for around 5 minutes.
Add the mince and stir until browned; drain any excess fat.
Add the chopped tomatoes and stir them through, then add beef stock and stir again.
Stir in the tomato puree, salt, chilli powder, cumin and mixed herbs. Mix well and turn heat down, leave mixture to simmer until reduced and thick.
Meanwhile, prepare the nachos. On a baking tray, layer tortilla chips and grated cheese until you have as much as desired. Pop it into the oven at 180 C / Gas 4 for 10 minutes, or until the cheese has melted.
Before serving, add sweetcorn and/or kidney beans if you wish.
Ladle chilli into bowls and use the nachos to dunk! Alternatively, you can pile the chilli on top of uncooked nachos, add more grated cheese and bake for another 5 minutes for a tasty messy treat!