This is really pretty simple. A distiller buys grains off the commodity market: corn, wheat, rye, whatever their recipe demands. They also buy malted barley from a supplier; none of the large Bourbon distillers grow their own grains or malt their own barley. Each grain is milled into meal, which takes specialized equipment for each grain, then everything is cooked together, with the addition of each grain happening at a different temperature. Starch to sugar conversion is allowed to take place (due to the enzymes in the malted barley), then fermentation is started, typically with a secret yeast strain. After this, everything is dumped into a column still, where a first distillation happens. This liquid (at about 80 proof) is pumped into a doubler still where a second distillation takes it to between 110 and 150 proof. The spent grain, historically fed to pigs is removed from the still and a portion of it is used to “sour” the next batch of grain, ensuring proper pH for yeast growth.
So glad you tried it and you liked it! The recipe is built quite directly on the modern version of the Trader Vic Mai Tai, including the nutty curry-leaf syrup in the place of orgeat and even the split rums.
Phenomenal drink, so this is nitpicking--but shouldn't this be a Jakarta Daiquiri? 2 oz. rum, 3/4 lime, 1/2 syrup is a pretty standard daiquiri, and adding a bit of Curacao isn't unheard of. Muddling 5 fresh curry leaves in cane syrup did the trick for me, and I strained onto new ice.