In a small mixing bowl, add the onion, beetroot, crème fraÎche, dill and allspice and combine. Pour in the balsamic vinegar and generously season everything with salt and pepper.
Peel the end of the horseradish root and then grate some into the bowl, about 1 tablespoon. Mix well, taste and add more horseradish to your liking; be bold.
Get a frying pan or griddle pan as searingly hot as you can. Lightly oil the steaks and season with salt and pepper. Fry them for just shy of a minute on each side until nicely coloured. Remove from the pan and leave them to rest for a few minutes.
Butter the bread and divide the salad leaves and beetroot mix between 2 slices. Top each with 2 steaks and then pop the remaining slices on top and tuck in.