1 1/2 oz of sloe gin
carbonated water (or sparkling water)
1 tsp of powdered sugar (or sugar)
1 of egg
1/2 of msr tequila (or Agavero Tequila Liqueur)
Shake ingredients (except carbonated water) with ice and strain into a highball glass over two ice cubes. Fill with carbonated water, stir, and serve.