Throw ingredients in a large saucepan. Bring to boil and cook for 30 min.
Add fish fillet in court bouillon, turn the heat off – put the lid on and let poach for about 5 min (Do not over cook nor stir).
Transfer fish fillet onto a plate to cool. Shred fish making sure there is none pin bones left behind; set aside.
Yields 16 to 24 balls /1.4oz/40g to 0.9oz/25g.
Bring water, butter and salt to a boil. Remove from the heat and mix in flour to combine – slide back on stove and cook pate a choux for a couple of minutes stirring swiftly. Transfer into a clean bowl, mix in the egg and add potato, fish, herbs and season with turmeric, salt and pepper to taste.
Using a small icecream scoop, make balls into desired size and chill.
Blend oil with herbs, sieve and set aside.
Whisk egg yolk, mustard, vinegar and seasoning. Pour herbed oil into thin stream whisking constantly.
Season with salt and pepper – for a firmer texture, use an immersion blender.
Store mayo in the refrigerator for up to 2 days.
Deep fry cromesquis in a 375ºF/190ºC oil in 2 batches. Tranfer onto a plate lined with paper towel.
Let cool down a bit and top with some herbed mayo right before serving or serve mayo in a separate dipping bowl. Bon appétit!