Preheat oven to 375 degrees. Prepare a sheet pan with parchment paper. Arrange walnut halves in a single layer. Bake for 5 minutes. Remove from oven and set aside.
While the walnut are in the oven, in a 2 quart saucepan combine sugar, coffee, curry powder, cayenne, pepper and salt. Cook and stir until sugar dissolves and comes to a boil. Stop stirring and insert a candy thermometer and cool until mixture reaches the soft ball stage (236 degrees).
Remove from heat, add vanilla extract and stir for 1 minute. Add walnut halves, stirring until all of the walnuts are well coated.
Pour mixture on parchment and separate using two forks.
Recipe by the modern barista at https://themodernbarista.com/index.php/2017/02/04/muan-jai-blend-spicy-curried-walnuts/