Add the agave syrup to a small saucepan and warm gently over very low heat just until fluid and pourable. Do not allow it to simmer or boil. Remove from heat, add the wide grapefruit peel strips, cover, and let steep for 20–30 minutes. This controlled infusion extracts aromatic bitterness and citrus oil complexity without pulling harsh pith compounds. Strain out the peels and let the syrup cool completely before using.

Rub a fresh lime wedge lightly around the rim of each glass. Dip the rim into coarse sea salt, rotating gently to create an even but restrained coating. Shake off excess salt — the rim should frame the drink, not dominate the first sip. Set glasses aside.

In a cocktail shaker, combine the fresh blood orange juice, red grapefruit juice, lime juice, grapefruit-infused agave syrup, and the pinch of fine sea salt. Fill the shaker with ice and shake hard for 10–12 seconds. This aggressive shaking chills the mixture rapidly while emulsifying citrus oils and integrating sweetness and acidity into a cohesive base.

Strain the shaken base into a large pitcher or directly into the prepared glasses filled with fresh ice. Top gently with chilled club soda. Stir once or twice only — just enough to integrate while preserving carbonation and maintaining brightness.

Finish with lime slices and twists of blood orange peel for aromatic lift. Serve immediately while cold, structured, and lively.