Make the basil bay-leaf syrup:

Combine demerara sugar and ½ cup  water in a small Stainless Saucepan over medium-low heat, stirring until sugar is completely dissolved.

Reduce heat to lowest simmer, add basil and bay leaves, and steep until herbs are brown or wilted on edges, about 30 minutes. Remove from heat and let cool slightly.

Strain liquid into a resealable container; discard herbs. Syrup can be refrigerated for up to 1 month.

Char the grapefruit:

Using a Paring Knife, cut grapefruit in half lengthwise.

Slice one half into ½”-thick “half moons.” Reserve remaining grapefruit for additional cocktails or another use.

Lay slices flat on a cutting board and sprinkle a small pinch of salt and granulated sugar over each slice. Flip and repeat on other side.

Heat an Enameled Cast Iron Skillet over medium.

Gently place grapefruit slices in Skillet and allow citrus to get a medium char on one side, 3–5 minutes.

Flip slices with tongs or a spatula to get a light sear on the opposite side, about 3 minutes more.

Set aside to cool, then use immediately or store in a resealable container in fridge for up to 2 days.

Make the cocktail:

Combine sotol, lemon juice, and basil bay-leaf syrup in a Drinking Glass.

Fill Glass ¾  full with ice and stir twice using a bar spoon.

Top with sparkling water and stir once gently.

Place charred grapefruit slices inside of drink, pressed against glass.

Add more ice as needed and garnish with basil leaves.