This is bartender Kevin Diedrich's ode to yesteryear. The bitterness of the Campari is balanced by passion-fruit-and-vanilla-agave syrup; the frothy drink tastes like an adult version of a soda-fountain favorite.

½ cup agave nectar
½ cup warm water
½ vanilla bean, split lengthwise
Ice
2 ounces tequila, preferably Partida Blanco
½ ounce lime juice
½ ounce passion fruit purée (see Perfect Purée for a source)
½ ounce egg white
¼ ounce Campari
One 12-ounce can cream soda
Lime zest

1. In a glass jar with a tight fitting lid, combine the agave nectar with the water and stir to dissolve. Add the vanilla bean, cover and refrigerate at least 24 hours. Strain before using.

2. In a cocktail shaker filled with ice, combine the tequila, lime juice, passion fruit purée, egg white, Campari and ½ ounce of the vanilla syrup. Shake well. Strain into a Collins glass filled with fresh ice. Top with the cream soda and garnish with lime zest.