For the Spice-Poached Beets:
Sous-vide the beets with whole allspice, cinnamon, and black pepper. Cook in a circulator at 85°C for 12 hours. Peel while still warm.
Set the liquid that results from cooking with gellan and use as a garnish in the finished dish. Chill the beets for service.
For the Buttermilk Vinaigrette:
Combine the buttermilk and crème fraîche, and season with salt and pepper.
To Assemble and Serve:
Slice the beet into cubes, but retain the natural shape for presentation. Season well. Dress the beets with the buttermilk vinaigrette. Very lightly dress the greens and herbs and season them. Spoon a line of dressing on the plate and place the greens over this. Add slices of baby beets to the greens, as well as the pistachio and beet gel. Spoon a few drops of the pistachio oil on the plate and on the beets.