How to Make It
In a medium bowl, whisk the sugar and 1/2 cup of salt with the vodka and the citrus zest and juice until the sugar dissolves. Place the salmon, skin side down, in a glass or ceramic dish lined with a large sheet of plastic wrap. Spread the sugar-citrus mixture evenly on the fish, then pat the beets on top. Wrap tightly in the plastic. Top with a plate and a few heavy cans to weigh it down. Refrigerate until the fish feels firm and looks cured in the center, 2 to 3 days. The sides of the fillet will have the strongest flavor and driest texture.
In a medium bowl, whisk the mayonnaise with the Dijon, dill and horseradish until smooth. Stir in the celery root and season with salt.
Rinse the cured salmon and pat dry. Slice very thinly across the grain and serve with the remoulade and rye bread.