Fermented vegetable water (1.5% salt)
white wine vinegar
cold cubes of butter
store bought mayonnaise
First reduce the fermented vegetable water till it weighs 100 grams. Then add the white wine vinegar and while mixing with a hand blender add the egg yolk. Directly blend some air in the mixture as well. After while beating it heat it up till the sauce starts to thicken and it’s cooked. Then turn off the heat and directly add the cold cubes of butter to prevent the sauce from overcooking. Now I also add a small amount of store bought mayonnaise. The stabilizers in the mayo will stabilize the sauce making it far more full proof when you want to reheat it. Now you can use it like this or transfer it into a siphon. In a siphon the hollandaise will become much airier, but it will be a lot easier or reheat it.