Heat the oil in a large non-stick frying pan and fry the onion and pepper for 5 minutes over a medium heat, stirring occasionally. Sprinkle over the chilli powder and stir-fry for 2 minutes. Add the spring onions, beans and chicken and simmer for 5 minutes until piping hot.
Cook the rice according to the packet instructions, then stir into the bean mixture. Season to taste.
Heat the wraps for 1 minute on each side in hot frying pan. Place half the rice mixture into the centre of each wrap. Sprinkle over two-thirds of the cheese. Brush beaten egg around the edge of the wrap. Fold the top and bottom over the filling, then fold in the sides to form 2 burritos. Serve with sour cream.