In a large pot, combine Elderflower syrup, honey, water, citrus peels, vanilla bean, and salt, whisking until well combined. Bring JUST to a boil, reduce heat, and simmer for 10 minutes. Remove from heat and allow to cool to room temperature.
Stir about 2 cups of vodka into the cooled syrup mixture, and taste. Continue adding vodka, to taste, until desired flavour / alcohol level is reached.
Strain through fine cheesecloth or a coffee filter, discarding peels. Funnel into clean wine or liqueur bottles.
After bottling, you should let it age for about a week in a cool place before drinking it – IF you have that kind of patience! Aging results in a smoother, more mellow flavor.