This cocktail comes from a little bar in Tokyo called The Drunkard, where they serve the herbs separate from the cocktail. We have taken inspiration from this and keep the mint separate, so you crush it with your chubby straw and get the fragrance right there.
In a Boston shaker, muddle the lime with a muddle stick, add the palm sugar and muddle to combine. Add the rums and half of the ice. Place a glass on the shaker and shake.
Pour into your serving glass, top with the remaining ice and garnish with mint leaves.