To make the celery seed simple syrup, add the cup of water to a saucepan, over high heat, and bring to a boil. Reduce the heat to a simmer and add the cup of organic sugar and the ¼ cup of celery seeds. Stir frequently, until the sugar dissolves completely. Remove the pan from the heat and allow the syrup to cool. Once cooled, strain out the celery seeds. Place the syrup into an air-tight bottle and keep refrigerated for up to two weeks.
To make the cocktail, place a tablespoon or two of the Bloody Mary Salt into a shallow dish. Run the edge of a cut lime around the rims of two cocktail glasses and dip them into the salt. Fill the glasses with ice and set aside.
Add the tequila, fresh lime juice and celery seed simple syrup to a cocktail shaker. Filled with ice, cover and shake well. Strain into glasses, top with the soda water and serve.