The Nonya cooking ingredient Daun Limau Perut or Kaffir Lime Leaves is from a variety of citrus known by the name of the leprous lime or the kaffir lime. The leaf has a subtle fragrance which gives a distinctive taste to many Nonya dishes.
Daun Limau Perut or Kaffir Lime Leaves are precious to many Nonya and Thai
dishes, from soups to curries and stir-fried dishes. They blend with lemon grass
and lime juice in tom yam to give the soup its wholesome lemony essence. In
soupy dishes, add the leaves whole or torn into smaller pieces, using them as
one would bay leaves to flavour broth or stew.
Daun Limau Perut or Kaffir Lime Leaves when young and tender, are finely shredded and added to salads and sprinkled over curries for a burst of flavour. Being rather thick, they must be cut very fine, like threads, and the thick mid-rib removed. To sliver Daun Limau Perut or Kaffir Lime Leaves finely, stack three to four leaves of similar size together and slice them very thinly with a sharp knife. It is faster to cut diagonally , which gives the hands better leverage, or roll a few leaves at a time into a tight roll before slicing. If fresh Daun Limau Perut or Kaffir Lime Leaves are not available, use the tender new leaves of lime, lemon or grapefruit. They won't have the same fragrance but are preferable to using dried Daun Limau Perut or Kaffir Lime Leaves in some dishes.
When making a soup or stock, whole fresh or dried leaves may be added, as they are removed after cooking. Finely chopped fresh or crumbled dry Daun Limau Perut or Kaffir Lime Leaves are used in dishes like tom yum, strir fries and curries, especially those containing coconut cream. The flavour also combines well with basil, cardamom, chiles, cilantro, cumin, curry leaves, lemon grass, galangal, ginger, mint, tamarind, turmeric and coconut milk.
Though the juice is seldom used in cooking, the peel of the fruit, with its high concentration of aromatic oils, is indispensable in many curry pastes and is one reason why Nonya and Thai curries taste refreshingly unique. The zest also imparts a wonderful piquant flavour to such delectable favorites as fried fish cakes, and it blends in powerfully with such spicy, chile-laden stews as "jungle soup" (gkaeng bpah). Because it's strong flavour can over power the more subtle ones in a dish, the rind should be used sparingly, grated or chopped finely and reduced in a mortar with other paste ingredients until indistinguishable..