In an casserole dish over a medium heat the oil. Add the onion, carrot and celery and cook for five minutes or until tender. Add tomato paste and beef mince and cook for a further five minutes. Add the tomatoes, kidney beans, Simon Gault Home Cuisine beef stock, Simon Gault Home Cuisine Mexican seasoning and brown sugar. Bring up to a simmer and then simmer for a further 25 minutes. Divide between 4 dishes and serve with fluffy rice, sour cream and thinly sliced spring onion.