Bring a small pot of water to the boil, then gently lower your egg into the water using a dessert spoon, so that it doesn’t crack. Boil for five minutes for a runny yolk, or slightly longer if you like it firmer.
Meanwhile, toast your sourdough.
In a bowl, combine the avocado flesh with the feta. Mash well with a fork.
Once the egg is done, run it under cool water and peel.
To serve, spread the avocado over the toast, tops with the egg (break it with a fork) and then sprinkle over the chilli flakes. Squeeze lime juice over the top, season with salt and pepper, and enjoy!