2 mint sprigs (1 for muddling, 1 for garnish)
3/4 ounce freshly squeezed lime juice
1 ounce simple syrup
1 ounce ginger beer, preferably homemade [see below]
1-1/2 ounces Tanqueray London Dry Gin
Muddle 1 of the mint sprigs. Mix it with the lime juice and simple syrup. Add the ginger beer, gin and ice. Shake well and strain into an ice-filled, 10-ounce highball glass. Garnish with the remaining mint sprig.