In a bowl, combine the flour, egg, corn and half the onions with some seasoning, then mix well. Mix the avocado with the remaining onions, lime juice, coriander and seasoning, then set aside.
Heat 1 tbsp oil in a non-stick frying pan. Drop tbsps of the corn mixture into the frying pan, smoothing them down to form cakes. Cook for about 2-3 mins on each side over a medium heat, adding the remaining oil if you need to. Serve hot with the avocado salsa, lime wedges and some warm refried beans.