Step 1

For lime-salt rim, pound ingredients in a mortar and pestle to just combine, transfer to a plate and set aside.

Step 2

Rub rims of tumblers with a slice of grapefruit to moisten and dip tumbler rims into lime-salt, pressing lightly, then fill tumblers with ice. Divide mescal and juice among tumblers, top with soda, add a squeeze of lime, garnish with a slice of grapefruit and serve.