I definitely love using roasted beetroots but I have also made this using raw or boiled beets. I prefer roasting the beets as this definitely delivers the best flavour, not to mention the colour which is simply incredible. That deep red you can only achieve if you roast them. Horseradish is a seasonal root and this is the time (April-May) to get hold of some but these days I can happily say it is available all throughout the year.