To prepare the taramosalata, start by soaking the bread in water, after you have removed its crust and then squeeze it, to remove the excess water.
Chop the onion in thick rings and mix it in a mixer with the tarama, until you get a soft cream.
Add half of the lemon juice and mix it again. Pour the olive oil slowly, whilst mixing.
Store the sauce in the fridge and serve it when it is cool.