In a cocktail shaker, dry muddle the Kaffir lime leaf. Add the gin, curried nectar, and lime juice with a full scoop of ice. Shake heavily for 10 to15 seconds. Fine strain into a chilled cocktail glass and garnish with lime wedge.
In saute pan, lightly toast the cumin seeds and coriander seeds. Combine the seeds with the allspice, black peppercorns, white peppercorns, turmeric, and chiles in a coffee grinder. Pulse the mixture 3 times to a medium grind.
In large saucepan, add the spices to water and bring to a boil. Add the sugar and stir to dissolve. Add salt and reduce to simmer for 10 minutes. Remove from heat and let cool 30 minutes. Strain through a chinois and refrigerate.