It you are using fresh, unprepared roe then place in a bowl, cover with water and set aside to soak for 30 minutes (this removes the excess salt). Clean the roe, drain well then crush with a few drops of olive oil until you have a paste.
Scrape the paste into a bowl and mix in the bread, olive oil and lemon juice (add these a little at a time, alternating between them).
While adding these ingredients beat the mixture with a wire whisk until it comes together as a smooth paste. Turn into a serving bowl, garnish with lemon