Bring water and sugar to a boil in a saucepan over medium-high heat. Heat to between 234 and 240 degrees F (112 to 116 degrees C), or until a small amount of syrup dropped into cold water forms a soft ball that flattens when removed from the water and placed on a flat surface, about 15 minutes. Lightly oil a baking sheet.
Remove the syrup from the stove, then stir in the vanilla extract, baking powder, cinnamon, and curry powder. Add the pecan halves, return the saucepan to the stove, and stir until the pecans are well coated with the sugar mixture. Continue cooking and stirring until the sugar sticks to and hardens on the pecans, about 5 minutes. Spread out onto prepared cookie sheet and allow to cool to room temperature before breaking into individual pieces.