Some leaves taste like nothing, but then there are other leaves that taste very, very good. Using leaves that taste good to flavour spirits is smart and correct but, unless you have an immersion circulator or fancy siphon, it can take days, which is too long. Luckily, you can speed up the process significantly with a blender.
Cocktail syrup is very easy — some would say “simple” — to make. Dump some sugar in some water, heat it until it dissolves, let it cool. If you want a flavour other than “sweet”, you can boil some sort of plant part in the water to impart something special. However, in the case of ginger syrup, this route can give you a dull, not-so-spicy syrup with a “cooked” sort of flavour.
According to PUNCH, bartender Dorothy Elizabeth uses this blend-and-strain manoeuvre to quickly infuse all manner of booze with bright, vibrant flavour and colour. (Click the link below to peep all of her crazy creations.) Similar to this no-cook ginger syrup, the slicing motion of the sharp blades extracts super fresh flavours in a matter of moments. (I tried it with the makrut lime leaves you see above, and can confirm it is an extremely efficient and effective infusion method.)
Just toss a cup and half of (de-stemmed) leaves into a blender (the higher powered, the better) with 750 milliliters of alcohol, pulse until the booze takes on a bright green colour, add a few squeezes of lemon juice to prevent browning, and pulse again. Strain everything through a coffee filter, and store in the fridge for up to three days.