Why This Works
At its heart the French 75 is a compact sour: gin, lemon, and a little sugar, held in tension, then stretched long with something sparkling. Get that small base right and the rest takes care of itself. Because there is no alcohol to add an edge, lean slightly brighter on the lemon than you might expect. The acid does the work the champagne's bite and the gin's proof used to.
The sparkling component is the whole personality of the drink. Real carbonation lifts the gin's botanicals up to your nose and gives the French 75 its celebratory rise. A genuinely dry alcohol-free sparkling wine is the ideal, but a good, cold club soda is a clean, low-sweet fallback that lets the gin lead.
Above all, keep it dry. A French 75 should read crisp and grown-up, not sweet. Half an ounce of syrup is plenty against the lemon, and the bubbles carry the rest. If it tastes flat, reach for a touch more lemon or a more juniper-forward gin before you reach for sugar.
The Alcohol-Free Swap
Alcohol-Free Gin brings the juniper and citrus-peel botanicals that make this drink sing. Look for one that leads with real juniper and finishes dry, so it holds its own against the lemon and the bubbles.