Fresh basil muddled with gin and lemon — bright, herbal, and completely addictive.
London Dry gin with juniper, citrus, and coriander notes is the classic choice — the botanical bitterness of the juniper plays beautifully against the fresh basil. Tanqueray is the most frequently recommended: clean, juniper-forward, and not too expensive.
Hendrick's (with its cucumber and rose petal notes) adds an interesting floral dimension that works well if you want a more delicate drink. Avoid very heavily botanical gins (Monkey 47, Gin Mare) — they compete with rather than complement the basil.
Replace basil with 6 fresh thyme sprigs. The woody, slightly medicinal quality of thyme is surprisingly excellent with gin and lemon.
Add ½ oz elderflower liqueur (St-Germain) and reduce the simple syrup to ¼ oz. The elderflower and basil are a genuinely beautiful combination.
Add 3 fresh strawberries to the shaker alongside the basil and muddle together. The strawberry sweetness lets you reduce or eliminate the simple syrup.
Add 3 slices of cucumber to the shaker before muddling. The cucumber amplifies the freshness of the basil and adds texture to the drink.