Lay two slices of smoked salmon on a plate and prepare the avocado.
Scoop out the avocado into a bowl and mash. Finely chop the coriander leaves and add to the mashed avocado. Add the lemon juice, salt, black pepper and chilli flakes and mix to combine.
Top the avocado mash with the tablespoon of sour cream.
Add the olive oil to a skillet and heat on medium heat. When hot, turn the heat down to low and crack the egg open, and drop gently into the pan. Cook until the white of the egg is opaque and firm and the yolk is set. This should take only a minute or two. Season with salt and black pepper.
When cooked, take the eggs out of the skillet, and place on paper towels to dab off the excess oil. Serve the egg on top of the sour cream
