This syrup mixes the zest of small, bumpy kaffir limes with the flesh of regular limes. (If kaffir limes are unavailable, you can use regular limes for both elements, although it won’t have that unique kaffir lime flavour, which mixes lime, lemon, mandarin and lemongrass. And you usually can’t use kaffir limes for their juice as their flesh is dry.) The syrup is a delicious addition to cocktails, and also great for non-drinkers — for the ultimate lime soda, combine 1 part syrup with 4 parts soda water (club soda), plus a squeeze of fresh lime and a sprig of mint.