['Cut the chilli into 10 slices and set aside five for the garnish. Put the galangal (if using), ginger, coriander and Thai basil in a cocktail shaker, and muddle (ie, bash) with a wooden spoon, gently mashing them to release their juices.', 'Add the remaining five chilli slices, rum, lime juice and coconut water, fill the shaker with crushed (or cubed) ice, and churn (ie, stir) just once to disperse the solids.', 'Strain into a tall glass filled with ice (crushed, ideally), the extra Thai basil and reserved sliced chilli, then arrange the mint on top. Use a sharp knife to splinter one end of the lemongrass into a fan, lay it horizontally on top of the glass and serve.']