1. Peel and grate the beetroot, keeping the pulp and juice together in a bowl. Stir in salt, sugar, vodka, and lemon zest.
2. Spread out ⅓ of the mixture in a thin layer on a baking sheet and place the salmon fillet on top, skin side down.
3. Cover the salmon with the remaining mixture. Wrap the whole tray tightly with plastic wrap and let the salmon “cure” in the refrigerator for about 48 hours.
4. When ready, scrape off beetroot mixture and discard. Wipe off excess salt with a paper towel.
5. To slice, start at the tail end. Hold a sharp flexible bladed knife at a 20-degree angle and cut the cured salmon flesh into thin slices, taking care not to cut the skin. Lift salmon off the skin and serve.