Heat the oil over a high heat and brown the mince in a shallow pan with a lid. Add the onion, pepper and chilli, and cook gently for 5-10 minutes or until the onion is soft.
Add the tomatoes, stock and kidney beans. Season with pepper and simmer, covered with a lid, for a further 20 minutes. Add the chocolate, stir together and simmer for a further 5 minutes.
Meanwhile, cook the rice according to the instructions on the packet. Garnish the chilli with the sliced spring onion and serve with the rice.