Put the eggs into a saucepan and add enough cold water to cover them. Bring to the boil, then turn off the heat and put a lid on for six minutes. Drain the eggs and rinse them under cold water and leave them in a bowl of cold water for 15-20 minutes. ( This can be done well in advance).
Shell the eggs, then cut them half, vertically. Scoop out the egg yolk into a bowl.
Cut avocado in half and remove its stone. Scoop out the flesh into a small food processor. Add the red onion and the deseeded chilli. Process until you get a textured paste, then add the coriander, lemon juice and process until you get a smooth cream. Take half of this cream out of the food processor and use it for guacamole or other avocado cream. Add the egg yolk and mustard to the remaining avocado in the food processor and pulse again for a few seconds.
When you get a creamy texture, season with salt and pepper to your liking, then taste and add more lemon juice or mustard if needed.
Fill the egg whites with the mixture, using a spoon or piping bag, then dust with paprika and scatter some chives on the top and serve.