Combine tequila, grapefruit juice, lime juice, simple syrup, and orange liqueur in a pint glass.

Fill the glass with ice.

Cover with a shaker tin.

Shake vigorously for 8 to 10 seconds.

Strain into a rocks glass filled with ice.

Garnish with cactus fruit peel.

To make simple syrup, put sugar and water in a small saucepan.

Cook over low heat, stirring, until the sugar dissolves.

Alternatively, heat in the microwave.

Store the simple syrup in a sealed container in the refrigerator.