The following is an online extra from our February Sourcebook issue, heading to newsstands now.

Casa del Barco's blackberry basil margarita (Photo courtesy HOUSEpitality Family)
New deal: Casa del Barco Beverage Director Michael Avery was developing a house-styled margarita for this modern Mexican restaurant in Shockoe Slip. He wanted nontraditional, yet clean flavors, not a processed, neon-green fishbowl ’rita.
Initial vision: More upscale, with fresh citrus and, for his own twist, juicy, flash-frozen blackberries, available year-round. But gold tequila battled the blackberries. The piquancies didn’t gel.
Another pairing: Avery thought of the herbaceous, floral qualities of agave — but which one? Unaged Juarez Silver Tequila complemented the triple sec and citrus. He didn’t want to mask the subtlety of an aged añejo in a drink.
Back to the drawing board: Blackberry juice created a muddy color when shaken with lime juice. Michael tried lemon. It worked! As a bonus, the lemon added pop and zing.
Presentation: Avery discovered that margaritas initially came in plainer glassware, like a double Old Fashioned. From a bartender’s perspective, this was a win — easy to clean and store — and the customer feels like they have a solid drink in their hand.
Back to the drawing board II: The drink needed sweetness. Michael added St-Germain, an elderflower liqueur. It sugared and incorporated more flowery notes. But he wasn’t done.
A finishing touch: Homemade basil simple syrup took the cocktail home. It accented the blackberries and added complexity. The margarita, strained over fresh ice, is a lovely dark blue that Avery describes as the color of the night sky before dusk. No garnish was needed.