Have 45 g of grated bottarga at the bottom of the blender cup or canning jar. Pour 50 g of boiling water on top of it, stir and let it set for about 2 minutes.
Get the immersion blender and stick it in all the way to the bottom. Activate the blender, keeping it still, for about 30 seconds.
Having the blender still at the bottom of the glass, add the oil on top of the bottarga-water mix. Start the blender and pull it up slowly as the oil mixes. This will give a uniform mayonnaise consistency.
If the mayo becomes too thick and you’d like to thin it out, blend water, 1 teaspoon at a time, into the mayo until you reach your desired thickness.
Grate lemon zest to give a nice citrus taste or season with your favorite spices.