Boil the water and add the semolina flour, stirring continuously. After few minutes, when the mixture has thickened, remove it from the heat and let it cool completely.
Finely chop, as you can, an onion.
Using an electric mixer, blend the fish roe with the onion, while gradually drizzling in sunflower oil. After 3-4 minutes, you will obtain a smooth, pale cream.
Add the cooled semolina porridge, breaking it into smaller pieces as you incorporate it.
Keep mixing gradually adding oil and a little lemon juice until you have a smooth, creamy paste.
Taste the spread and adjust the seasoning with salt or more lemon juice if you think it needs it.
Video
Notes
Taste the fish roe before you start preparing the spread and add salt only if necessary towards the end.If carp roe isn't available you can use instead cod, salmon, or any other white fish roe.If you're not a fan of semolina, you can easily substitute it with soaked and squeezed crustless bread (a common ingredient in taramosalata) for a lighter texture.