Let's take a minute to appreciate two underdogs of the citrus world: lemongrass and kumquats.
Okay, so lemongrass isn't really citrus at all, but the herbaceous and lemony flavor of its reedy stalks improves most everything it touches. Though lemongrass meets its highest purpose in complex curry pastes with fried shallots, moody chilies, and nutty coconut, the stuff makes some fine custard: delicate and light with a touch of perfume. And it's even better when combined with sharp citrus.
Which is where the aggressive tartness of kumquats comes in. These little fruits—currently abundant in the Chinese markets surrounding our office—are a pain to prep but seriously rewarding. They have the rounded sweetness of a Meyer lemon but with way more sass, and a tropical lilt that plays well with the aromatic qualities of lemongrass.
The trouble with kumquats is their overwhelmingly sour juice, not to mention their tiny yield within a thick rind and studs of large seeds. But the feisty kumquat is easy to tame: candy it, skin and all, and you have an entirely edible fruit with the complex bitterness of marmalade and sweet-tart flesh that's much easier to love.
To candy citrus properly you need to watch your temperatures and cooking time. Which is why, for this ice cream at least, I don't bother. Were I serving candied kumquats at room temperature with cake or cheese, I'd go the extra mile. But this is ice cream. Cold messes with texture and flavor, and I found that by tossing minced kumquats with sugar and letting them sit overnight, I was able to soften and sweeten the fruit enough so it'd stay pleasantly sweet and chewy, even when frozen.
This recipe really gives you two gifts in one. The first is the ice cream itself: full of bright kumquat sweetness bolstered by cool lemongrass and rich egg. The second is a bonus: the syrup you get from faux-candying the kumquats overnight. You can drizzle it over this ice cream for sure, but also consider adding a spoonful to an Old Fashioned filled with ice. Stir in a light spirit—gin, light rum, and cachaça all do nicely—followed by a spritz of lemon or lime. Stir, letting some of the ice melt before sipping.
Southeast Asia: 2. Winter: 0.