White grapefruit tart with sweet rye crust

For the crust:

rye flour

all-purpose flour

cold unsalted butter, cut into small pieces

kosher salt

sugar

vanilla mixed with 1/4 cup ice water

For the curd filling:

egg yolks, lightly beaten

sugar (I used demerara, white will work just fine)

Juice of one white grapefruit (they tend to be large, if yours is smaller, you may need two: mine produced a scant cup of juice)

cold unsalted butter, cut into small pieces

Zest of one white grapefruit

For the candied grapefruit slice garnish:

large slice of grapefruit, taken from the middle of the grapefruit you use for juice

sugar

water

Special equipment: 9 inch tart pan with a removable bottom