Lime wedge
Fleur de sel or Kosher salt
Small handful nasturtium flowers and leaves (torn into pieces if large)
1/2 ounce agave nectar
1/2 ounce freshly squeezed lime juice
2 ounces freshly squeezed grapefruit juice
2 ounces blanco tequila
Ice cubes
Club soda, chilled
Grapefruit wedge and nasturtium flowers, for garnish

Moisten the outer rim of a Collins or highball glass with a lime wedge and coat with salt. Muddle the nasturtium flowers and leaves, agave nectar, and lime juice in the bottom of a cocktail shaker. Add the grapefruit juice and tequila. Fill the shaker with ice and shake well. Strain into the prepared glass. Add ice, top off with club soda, and stir. Garnish with the grapefruit wedge and nasturtium flowers.