For the avocado sauce, first remove the pit and peel from both avocados, put them in a bowl and mash them with a fork (you can leave the pieces bigger or smaller, depending on your taste).
Finely chop the spring onion (quantity 2 to 3 stalks depending on taste) and add. Then add sour cream, creme fraiche and lemon juice of half a lemon and mix it all together.
Finally, season the avocado sauce with salt, pepper and lemon zest.