To make the guacamole, scoop the avocado flesh into a bowl and mash with a fork. Stir in the chopped chilli, coriander and lime juice and season to taste with salt. Cover and set aside in the fridge.
To make the nachos, preheat the oven to 200°C/400°F/gas mark 6. Mix the refried beans with a bit of water until they are easily spreadable.