Chop up and fry the onion, carrot, and green pepper, until softened. Add the beef mince and stir in until browned. Add the kidney beans, chilli powder, cayenne pepper, and mixed herbs. Cook for 2-3 minutes. Add the chopped tomoatoes. Simmer on a low heat, with the lid on, for 15-20 minutes, until the mixture has achieved the desired consistency. Meanwhile, heat the oven to 225C and cook the chips for 15 minutes or so, turning them over half way through.