Freeze the beef sirloin or tenderloin uncovered on a tray in the freezer for 12 to 24 hours until fully rock-hard. Freezing uncovered prevents ice crystals from forming on the surface.
1 lb beef sirloin or tenderloin
Sharpen and hone a razor-sharp slicing knife just before slicing. Place the frozen beef on a chilled cutting board and slice 1-2mm thick slices quickly to keep the meat frozen.
Arrange the thin slices flat on a chilled serving platter or layer with parchment paper if stacking. Keep the platter chilled in the fridge until ready to season and serve.
Sprinkle coarse salt first over the beef slices, then drizzle fresh lemon juice and add finely grated horseradish. Add chopped onion and fresh dill if using for extra flavor.
2 tsp coarse salt, 2 tbsp fresh lemon juice, 2 tbsp finely grated horseradish, 0.25 cup chopped onion, 2 tbsp fresh dill
Serve immediately with small glasses of chilled vodka or ice water on the side for rinsing between bites. Optionally serve with sour cream.
0.25 cup cold vodka or ice water, sour cream
