Bai Makrut — Kaffir Lime Leaf & Rind Applications / ใบมะกรูด

Pan-Thai — the tree is cultivated throughout Thailand; Southern pastes use more rind; Central uses primarily leaves

Kaffir lime (Citrus hystrix, now more accurately called makrut lime) provides two distinct ingredients: the double-lobed leaf (bai makrut) and the intensely fragrant, bumpy rind (phiu makrut). The leaves are one of Thai cuisine's most distinctive flavour compounds — they contain citronellal and limonene in a high concentration that gives the fresh, floral-citrus top note to green curry, tom kha, and many stir-fries. Leaves are added whole to long-cooked dishes for infusion, or fine-chiffonaded for finishing. The rind (without pith) is pounded into curry pastes, particularly green and yellow, contributing a deeper, more bitter citrus dimension than the leaf. The juice of the fruit is rarely used in Thai cooking — it is astringent rather than sour.

The kaffir lime leaf's floral citrus note is one of the most recognisable identifiers of Thai cuisine globally — in green curry, it is the aromatic that separates the dish from any other green curry tradition.